Home

Loft floor joist size

Browse The B&Q Nail & Screw Range. Buy Online Or Collect In-Store Snag the Most Popular Trends in Women's Fashion With LOFT. Best Sellers Today. Find Fresh Takes on Feminine, Versatile and Affordable Women's Clothing at LOFT Today

Floor joists are normally closer to 150-200mm deep, (or 6-8 in old money) and would normally be at 450mm centres. / Loft Conversion - Floor joist thickness / support structure lay 3' x 2' beams down the middle to support the existing structure. Lie 4' x 2' beams down the side of the existing 3 x 2 beams True floor joist span calculations can only be made by a structural engineer or contractor. This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on-center (o.c.) for 2-grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load, which is typical of normal residential construction 400mm is good practice - it depends on hte size of the timber being used - span and load expected

Joist End Repairs kit of parts - steel plates and coach screw

Expert Help & Advice · Big Brands · 1000s Of Product

  1. imum requirement for 8 foot (2.44 m) lengths. A better choice would be using a 2 x 10 (50.8 x 254 mm) joist size
  2. Firstly, check to ensure that your joists are strong enough to cope with the additional loads of loft storage and the weight of a person moving around the loft. Trusses in new build homes are designed and built to allow for 25Kg/m2 of storage plus the weight of a person walking in the loft
  3. Span tables for timber floor joists. Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors. These tables can help calculate whether floor joists are strong enough to support themselves and the load they carry, without the help of any walls underneath
  4. imum allowable joist size given the above scenario: Therefore given the above example, the
  5. The joists are only 3x2, so my plan is to raise these by gluing and screwing 4x2 along the length of them which would then give me 170mm, and also reinforce them so I don't need to worry too much about weight. I'll then put some 4x2 going the opposite direction to take me to 270mm, and then board on top
  6. 1.2 Timber strength class and joist size. Automatically calculate suitable sizes. C16 (cost-effective, for most applications) C24 (stronger, more demanding) C14 C18 C22 C27 C30 C35 C40. or. Enter a specific size. Timber strength class. C16 C24 C14 C18 C22 C27 C30 C35 C40. Width ↔

we do alot of loft conversions and the floors have to be totally dependent of your existing joist with a 25mm gap. when the new joists are put in place we have to put chicken wire up and around every joist so the 100mm insulation doesn't bridge the 25mm air gap required. nearnwales, Oct 28, 2006 #1 The storage loft floor framing uses three 2″ x 4″ (38 mm x 89 mm) support joists. One of the support joists attaches to the wall frame. The other two support the storage loft floor. The supporting joists attach directly to the first floor loft frame which provides additional stability to the tiny house This is part 2 in my series of loft conversion videos. In this video I show how I cut my my joists, make packer plates, get the joists from the garden up int.. Attic joists that are made from 2x8s may be acceptable for building your attic floor, but because every room is variable, there are no absolutes. Joist dimensions are only part of the equation. You also need to ensure that the joist spacing is adequate

Loft conversion floor joist spans see description you attic flooring 101 all you need to know bob vila beefing up attic joists for living e jlc online can you convert your attic to living e board vellum. Whats people lookup in this blog: Minimum Floor Joist Size For Loft Conversio The additional joists will usually be required to be anywhere from 200mm to 225mm in depth and will rise above the ceiling joists in order to form that new floor structure. Should the current load bearing walls not be strong enough for this, additional steels or timber beams can be utilised to ensure adequate support for the new floor joists These joists (often 200mm or 225mm in depth) will rise above the tops of the current ceiling joists to form the floor structure. Depending on their span they will bear either directly on to the existing wall plates of external and internal load-bearing walls, or on to newly installed beams. New Bedroom and Ensuite in Dormer Loft Conversio The frame for the curved part of the loft will consist of three 2 x 8s, attached at an angle to give as much support as possible to the curve. The exact dimensions will depend on the size of curve desired. For this project, the frame for the curve will extend 2 feet from the main loft frame The new elements which help to form the new loft room(s) are broadly: Floor & beams; Walls; Doors; Floor & beams. It is unlikely that the existing ceiling joists will be adequate to support the weight (loads) that arise from the construction, contents and use of a typical habitable room developed in a loft

Floor Joist Size, Span and Spacing Table. by Joanna Stewart. Thu, Sep 13, 2018. Article may contain affiliate links. As an Amazon Associate I earn from qualifying purchases. When building a house or even a deck, it is important to confirm you have the correct joist sizes, spans and spacing before you get started We've moved into an old house and want to utilise the loft space, currently there's 3'x 2' joists which run for 6 m across the house, supported in the centre by a dividing wall. Each joist is therefore unsupported for around 2.8 m between each bedroom wall. We understand we need to strengthen the current structure, but how The new floor joists of your loft conversion will need to offer at least 30 minutes' worth of fire protection, which could mean replastering the ceilings in those first floor rooms below. The loft room will also have to be separated by a fire door, either at the top or bottom of the new stairs Understanding Floor Joist Spans. Floor Joists And Support Beams For Loft Conversions. Timber Joists And Other Materials For Loft Conversions Chion Merchants In London Surrey Kent. Can You Convert Your Attic To Living E Board Vellum. Best Method To Strengthen A Loft Floor Avforums All our standard size loft hatches are designed to fit between 600mm joist centres. 600mm is the standard width between the centre of the timber ceiling joists in the loft, this has been a requirement of UK Building Regulations for many years so applies to a good number of properties

These joists have been removed, to make way for the new floor joists for the loft conversion. The problem is the house over the 104 years has settled, leaving a 200mm difference in the height of the existing wallplates (from the front wall to the rear wall). To overcome this, the way i see it, i have 3 solutions If the height of the wall plate doesn't work for your loft, as in the case of a gambrel shed with 4' knee walls, then you can attach the floor joists to the rafters or truss above the walls to reach the desired height for the loft floor. Your loft ceiling should be a minimum of 6' above the shed floor to provide for adequate clearance. If you plan on attaching the joists without the.

SKIP19B LOFT FLOOR SCREWS 50 PACK - DIY at B&

  1. Shop Over 20,000 Products At Your Local Shipley Branch. Shop Flooring And Other Construction Materials At Toolstation
  2. Full answer is here.Regarding this, what size floor joists do I need? Looking at this table you will see there is a choice in the size of floor joist (2 X 6, 2 X 8, 2 X 10 or 2 X 12) and there is a choice in the joist spacing (12, 16 or 14). The floor joist spacing is the distance between the centers of any two installed joists.. Subsequently, question is, can you cut loft joists
  3. However, I'll try to answer your questions. So, Douglas Fir Larch grade Select Structural 2x8's at 16 on center spanning 12' can support 40 lbs. per square foot (psf) live load plus 10 psf easily. Likewise, your Table says Northern Species (whatever that is) 83x 400 can support a floor load spanning only 2.41 m. with a grade of Select.
  4. Cabin Forum/Blog: 16x30 cabin with 10 deep by 16 wide loft on either ends. Lofts will be for sleeping only and will only have a bed and maybe a small dresser. The WI construction standard calls for 40/10 live and dead loads and L/360 deflection for FLOOR joist. Since this is a loft, i think the specs for ceiling joist w/ attic storage would be sufficient
  5. The most common loft opening size is 562mm x 726mm in the UK. Which is 56.2cm x 72.6cm. Or 22″ x 30″ in inches. Standard loft hatch sizes can only really be used with a traditional extension ladder, that is placed inside the framework of the loft hatch to allow you to climb in and out of the loft
  6. The floor joist spacing is the distance between the centers of any two installed joists. See the image below for an example of joists spaced 16 on center (16 o.c.). Since the example house we are designing for is 12 feet wide, we need to find, in the floor joist span table, a joist size and centering that can span 12' or wider
  7. 2x4 2x6 2x8 2x10 2x12. Grade. Select Structural No. 1 No. 2 No. 3 Stud Construction Standard Utility. Member Type. Floor Joists Ceiling Joists Rafters (Snow Load) Rafters (Roof Live-Load) Deflection Limit. L/720 L/600 L/480 L/360 L/240 L/180. Spacing (in) 12 16 19.2 24

+1 Double check size of lumber .vs. weight loading capacity. Typical 2×8 length limit used as load bearing floor joist 16 OC is ~10-12ft for SYP. SPF framing lumber is shorter. Might want to look at IRC (building code) chapter 5, Floor Joist spans table. +1 Add a ledger board, and use face mount joist hanger's The 2015 IRC includes a new table R507.5 Deck Joist Spans for Common Lumber Species. The table makes it easier for deck builders to accurately size deck joists and for inspectors to check decks for adequate framing. Figure R507.5 Joists with Dropped Beam shows the optional cantilever and the end points of the joist and cantilever spans The widest span in the floor joist span table in Part 2 of this tutorial module showed that floor joists can span 17'2 if they are 2 X 12s spaced 12 o.c. (on center). Let's expand our house beyond that 17'2 span capability to 24 feet wide. So the house dimensions will now be 24' X 13' Beyond the size of joists, the spacing between them should also be taken into consideration. Standard joist spacing for the installation of attic flooring materials is 16 inches on center (OC.

LOFT Outlet Online - LOF

  1. 8,463 satisfied customers. We are looking at attding a loft space over a kitchen area. We are looking at attding a loft space over a kitchen area in a small home. The adjacent 2nd level is recently built attic space with 2 x 10 standard lumber floor joits The span acorss the kitchen is read more. walkereng
  2. The longer the distance between the supports, the greater the deflection for a given joist size. 4x2 may work for you - when I had my loft converted, it had to be 8x2!! There will probably be a difference though in what will flex when you walk on it, and meeting the loading requirements for habitable rooms as defined in building regs
  3. Bridging should comprise of solid timber with a depth at least ¾ the depth of the floor joists. I.S. EN 1995 states that bridging is required in all floor joists where the span is greater than 2.7 m at centres less than 1350 mm. Diagram C130 - Typical detail to ensure rigid floors
  4. An engineer can also design custom variations, such as an irregular distribution of roof joists, which makes it possible to fit in a skylight, a loft, and other features. Roof joists vary in size, depending on the material used and the requirements of the job

Loft Flooring From Chipboard To Hard Wood Floors. Reinforcing Weak Floor Joists With Steel You. See also Live Oak Homes Ponderosa Floor Plan. Attic Renovation 7 Things You Need To Know. Reinforcing 2x4 Ceiling Joists Building Construction Diy. How To S Attic Floor Joist Size And Ing. See also Diy Outdoor Dance Floor Floor Joist Size For Loft Conversion. By Review Home Co | July 11, 2018. 0 Comment. Loft conversion floor joist spans see loft conversion attic floor joist size and ing loft conversion floor joists diynot. Pics of : Floor Joist Size For Loft Conversion. Loft Conversion Floor Joist Spans See Description Yo Determining Load Limits. First, determine the size, the spacing and span, and the species and lumber grade of your floor joists. Look for a stamp on the joist that indicates the lumber's species and grade. Use a design value table to find the Fb value for your floor joists. As an example, consider a room with a floor area of 10 feet by 11 feet. floor joist size for loft conversion (+rsj) 4 posts • Page 1 of 1. by windy55 » Fri Apr 24, 2009 8:33 pm . Hello I'm about to embark on a loft conversion (mid victorian terrace) the span is 5.8m and the designer has spec'd 250 x 50 c24 joists at 400 centres Height is really tight so even slinging them between the existing joists i'll still.

What size floor joists do I need for a loft conversion

length of a and the size of the joists. Example: a=8', b=2', Posting Spacing=10' Refer to the Joist Span table. For an 8' joist span, either 2x8s at 24 O.C. or 2x6s at 16 O.C. are acceptable. For sizing the beam, use a joist length of 10' (8'+2') and a posting spacing of 10'. The Beam Size table indicates that th If this is the case with your structure, use the Floor Joist Table to determine maximum joist length/load. For example, the highlighted cell (below) shows that a 2 x 6 Southern Yellow Pine joist, with a grade of #2, and spaced 24 apart can have a maximum span of 10 feet - 0 inches (10-0), if you are designing your structure to support a. Basic loft insulation, which is required for either a warm or cold loft, is inserted between the joists or rafters. This may then be boarded over, but 270mm will probably come up over the joists. Therefore it's important to raise the boards, to prevent restricting ventilation and overheating electricity cables Maximum floor joist span for No. 1 and No. 2 Grade of Douglas fir are indicated below. Max. dead load (weight of structure and fixed loads) 10 lbs/ft 2. Live load is weight of furniture, wind, snow and more.. 1 psf (lb f /ft 2) = 47.88 N/m 2; 1 ft = 0.3048

Fixing the Loft Boards to the Ceiling Joists. The long sides of the loft boards should be laid at 90 degrees to the joists and the ends of every board should always meet on a ceiling or floor joist. All fixings to the joists or rafters should be done by screwing the panels down. This avoids the vibration caused by hammering nails through the. Floor Joist Sizes. In the past, 2x4s or 2x6s were sometimes used as floor joists. This size is no longer acceptable when framing a structure. In general practice, 2x8s, 2x10s or 2x12s are used when framing a raised floor instead. The exact size necessary may be stipulated by the building code required for a particular structure

Understanding Floor Joist Spans - The Spruc

In smaller lofts, it is often the case that the floor joists themselves will be used to support the sloping rafters. This is possible by constructing a dwarf timber stud wall 1m to 1.5m high, known as an ashlering, between the two. With the supporting ashlering in place, the internal struts and braces can now safely be removed. 5 1. I've found this page of Common Domestic Floor Joists Sizes. The dimensions of the joist depend on the span as well as the load it's intended to bear. From the table the minimum is 50x97mm which is approximately 2x4 in, but it doesn't give any indication of the load that that will bear. Share As the loft is small, the suggestion is that the load is reduced from the 1.5Kn to 1Kn. Also current ceiling joists are at 400, so the plan is floor joists at 200 centers to reduce the load per floor joist even more. So the recommendation from the BC who will be signing it off is 200 ctrs, 7 x 2 joists to support the floor and roof (dwarf wall Measure the area you plan to board out (multiply the width of the loft by its length). Take measurements in metres, this makes it easier when you are buying boards. Standard boards are commonly available in two sizes: 2,400 x 600mm and 1,220 x 320mm; and either 18 or 22mm thick

Loft joist standard sizes and distances - MyBuilde

Many people like to use the loft space as storage, however, so will insulate only to the top of the joists and then attach chipboard directly to the joists making a solid, walkable surface. Obviously if you install 300mm this is not possible, so prior to STEP 4 above, you will need to install loft stilts (or loft lifters ) Leave enough space for each floor joist every 15 inches or so. Leave enough space for the boards along the four directions of the loft. By doing the above, it will be easier for you to measure the size of the lumber you will need to build a garage storage loft

Cabin Forum/Blog: I m building a 16x16 with a second floor but low enough that it s still under 300sq foot. It s on peirs 9 of them them beams are 3 2x10 the space between them are 6 10 inches the span between the beams. I was going to use 2x12 for the floor joist is that overkill can I use 2x10 I don t want any sag in the floor. Thanks please help I m reading to start on the floor!! 24 ft span floor joist. I am building a loft in my barn, it will be 24 foot wide by 60 foot long and 7 feet tall. I was trying to keep the middle span open underneath the loft. I was planning on using 2″x12″x16′ joists, they would overlap by 8 ft in the middle. I was going to use 4 bolts, nails and heavy duty adhesive relative to the loft area. Unfortunately, anyone who is over 5' 9 has to duck to walk up there. I would like to reduce the floor joists from 10 I joists to 2 x 6 Yellow Pine. Unfortunately, the run is approx. 15 feet, which exceeds code. Is there anyway I can overcome this, for exampl

Joist size for loft storage - MyBuilde

38x72mm Mini Mini Joist Hanger is a timber to timber joist hanger suitable for light duty applications such as trimmers, ceiling joists and decking. The hanger is produced from 1mm thick pre-galvanised mild steel. The tag on the base of the hanger helps avoid rotation and aids fast, accurate lo.. £0.52 (£0.62 inc VAT How many Loft Storage Stilts you need depends on a number of factors: 1. The size of the loft storage platform you want to create 2. The type of the loft boards you use 3. The distance between your loft joists Size This will depend on how many things you have to store, remember building regulations recommend only Ok, to give you an idea generally floor joists are either 175mm x 50mm or 225 x 75 at 600 centres, which are sized to take the constant loads of furniture and the weight of people. The size you have in your loft are pretty typical and are not able to actually take a heavy constant load The same methodology would be applied to the other side of the loft. You'll see veritcal 2x4 wall studs with a doubled 2x8 ledger supporting 2x8 joists. * all lumber is douglas fir-larch structural grade. * ledger board: doubled up 2x8 attached to the 2x4 wall studs with two 1/2 x 6 lag screws at every wall stud When installing loft boards, it is important to ensure that the insulation within the loft is not squashed down, as this reduces the effectiveness of the insulation and can lead to condensation which will often result in damp, mould and rot. Therefore, if the insulation lies above the roof joists the loft floor will need raising

Floor Joist Spans for Home Building Projects Today's

Ceiling Joists I have actually currently laid a tongue & groove chipboard flooring but taking a look at your website wonder if I ought to possibly take this up and include a second set of thicker floor joists for strength, supplementary loft conversion information with Loft Conversions Basingstoke ( specialist-loft-conversion-in-basingstoke.co. The most common floor joist spacing's are 24 inch, 12 inch and 16 inch. The reason for these spacing is for a 4×8 sheet of plywood to fit without having to cut the sheet. If you have ever used a full sized framing square its size is 24 inches by 16 inches which works out perfectly for laying out a 24 inch joist spacing or a 16 inch joist.

Removing Bracing Studs From Attic Trusses Diy Home Improvement Forum. Read This Before You Insulate Your Attic Old House. Floor Joists And Support Beams For Loft Conversions. Hanging Ceiling Joists From A Beam In Attic Structural Ering General Discussion Eng. Strengthen Loft Floor Posh Pics Page 1 Homes Gardens And Diy Pistonhe Uk Reframing the loft hatch will have to be done if you install a loft ladder, or do anything else which changes the size of the opening needed for access into your attic. Read the full answer. How to Enlarge a Loft Hatch New opening marked on joist tops with 4 inches added either side to compensate for timbers

FSC Standard Kiln Dried Regularised C16 Treated Carcassing 220 x 45mm. FVRT4522. SKU: FVRT4522. Trade Sign in or apply for trade prices. £ 11 .88 inc VAT per metre. Loading. More details. FSC Standard Kiln Dried Regularised Treated Carcassing 70 x 45mm. FVRT4570 Step 2 Span Table: Select the appropriate table in Span Tables for Joists and Rafters. The Table of contents indicates that Table F-2 matches these loading conditions. Using Table F-2 (Figure #3), check each lumber size to see if a 16-inch spacing will permit a span of 15 feet 1 inch Downstairs 400 SF and upstairs sleeping loft. Floor joist are 2x10 16 O.C. Vinyl siding and cedar shakes with cedar shutters and accents. Metal roof. Double pane energy efficient windows. Full size kitchen. Granite counters. Full size side by side refrigerator. stackable washer and dryer. 50 gallon entergy saver hot water heater The average cost of a Manchester loft conversion in 2021 varies depending on the size and scale of the property you are converting. Generally, a loft conversion in Manchester costs between £16,000 and £50,000. Generally, converting your loft in the North West is much cheaper than in other areas of the UK (such as London and surrounding areas) TeleBeam is a totally pre-fabricated, entirely bespoke and adaptable loft conversion system for a wide range of roof spans and pitches. It is suitable for older style cut roof or a modern truss roof; bungalows, houses (detached, semi or terrace) barns or garages

Floor Joist Spans for Home Building Projects | Today's

A nice front porch, 5' wide double shed doors, huge loft area, and large floor space downstairs to use for your workshop, craft 12x16 storage shed building plans for instant download. 12x24 shed building floor plan33 viewsshed floor plan size of 12x24 with 6 and 12 inch overhangs and 36x36 inch window Free UK Delivery on Eligible Order In general terms, joists spaced 16 inches on center can span 1.5 times in feet their depth in inches. A 2x8 up to 12 feet; 2x10 to 15 feet and 2x12 to 18 feet. The larger the deck, the larger the joists. In typical deck construction, with a ledger on one side of the joist and beam on the other, the size of the joists is driven by the size of.

I have a 24'x 24′ gabel roof garage with loft for storage. loft is made from 2″x 8″ joist spaning across 24′, 24″oc with 1/2″ plywood floor. Rafters are 2″x 6″ 24″ oc, set on 2″x 8″ ridge board, notched on to walls. the roof has 7-12 pitch. the joist sit on top of 2″x 4″ walls nailed to rafters Table Notes Spans are based upon continuous support of compression flange over the full length of the joist. Calculated allowable properties are based upon AISI S100-07, North American Specification for the Design of Cold-Formed Steel Structural Members. For two equal spans, the listed span is the center-to-center distance from either end to the center support Q. Is there a simple way to size floor joists? A.Carl Hagstrom responds: The rule of thumb that I like to use when sizing uniformly loaded residential floor joists is half the span plus two. First, round the clear span of the floor joist up to the nearest foot, and divide by two. Then add two to the answer

Large Span Unsupported Floor / Ceiling Joists | Roof

Video: joist thickness for loft conversion DIYnot Forum

The two floor rsj's are spaced at 4metres 600mm in between to form floor area.Joists spaced at 400mm centres. The length of new dorma is 4metres 150mm,x3metres. I am assuming the size of floor joists are 225x48mm @400mm centres with one double joist to support stairs. Dorma joists 150mmx48mm Step 2 Span Table: Select the appropriate table in Span Tables for Joists and Rafters . The Table of contents indicates that Table F-2 watches these loading conditions. Using Table F-2 (Figure #3), check each lumber size to see if a 16-inch spacing will permit a span of 15 feet 1 inch Joist Span Table for Floor Joists Floor Joist Span Tables for various Sizes and Species of Wood. Joist span table - Use these tables to determine floor joist spans based on grade of lumber, size of joist, floor joist spacing, and a live load of 30 lbs/ft 2 or 40 lbs/ft 2.These tables can also be used to determine deck joist span

Loft conversion gallery

24 x 24 = My loft will be but 5' tall, due to staying within planning regulations size (30sq m x 4m tall peaked roof max), and the downstairs is going to be 8' headroom, so there is a limit to how. An older load table that I have (1979 Architectural and Graphic Standards) shows only 12 and 16 spacings for floor joists. For a 40 lb/ft 2 load and 16 spacing, lumber with modulus of elasticity E = 1,000,000 can span 13'11; E = 1,200,000 can span 14'9. This is based on deflection

Loft Conversion steel beams - YouTubeMark Brinkley (aka House 2Roof Hangers & Joist Hanger Fixed To Face Of Wall Plate

It might be a good idea to make a drawing of the floor joist as a reference. Be sure to jot down your measurements and mark it on the diagram so you have a good record of where they go. Step 4 - Reinforce the Floors. You will have to use a very sturdy piece of wood or some steel plating to reinforce the floor joists. Now it is time to use some. I need some advise on the size of floor joists to be used in a loft conversion. The longest span needed is 4.130m. From the building regs, table A1, i only need 195 x 50mm at 400mm centres, but I want to put 1.2m high stud wall supporting the slate roof at midpoint All our standard size loft hatches are designed to fit between 600mm joist centres. You'll notice most of our loft hatches are geared to suit a width of 560mm. If you can't find a standard size loft hatch to fit we can make you one to measure. See further below for information on our made to measure loft hatches Attic without storage: Use Table R802.4 (1) Ceiling Joist Spacing: 12 inches. Species and Grade: Hem-fir #2. Lumber Size used: 2×8. Now lets find the maximum allowable span for a 2×8 member given the above scenario: Therefore given the above example, the maximum allowable span for a 2×8 member is 26′-0″

Building a bed loft2 story Modern House Plan with a main floor master suiteStorage sheds, playsets, arbors, gazebos and more

My loft hatch is a standard uPVC which is about 620mm x 520mm in size. The current joists measure about 35mm thick x 96mm tall and are spaced about 560mm apart. I have some plumbing in the loft (not much, my control unit just for my Triton Digital Shower) and three up-lighters from the bathroom By reinforcing the 2×6, or whatever size you chose for the joists, you make the rectangle shape stronger. Whatever the purpose of the floor is, one thing is for sure that it will need to be able to support the weight. Think about each room as you are building, and keep in mind each one will have to be filled with equipment or personnel that. Check the existing ceiling joists, these are generally 4x2 and are not designed to carry much loading such as required by a living space. New floor joists ranging in size from 6x2 to 8x2can be fitted between the existing ones to form a separate floor above the ceiling joists The wooden joists or beams over your garage help hold your roof in place. If you have an attic over your garage, these joists also bear the load of your attic flooring and any materials you store in the attic. If you need a storage area above your garage, strong ceiling joists are necessary to support the added weight common to install new floor joists to allow for the extra loads from use as living space. Floor joists (grade C16) are sized from Eurocode 5. 47 x 145mm joists installed at 400mm centres will span up to 2.89m . 47 x 170mm joists installed at 400mm centres will span up to 3.38m . 47 x 195mm joists installed at 400mm centres will span up to 3.87 Roof pitch between 15 and 22.5 degrees with rafter spacing strength class C16 Size of rafters in mm 400mm 450mm 600mm; 100 x 47: 1.81: 1.78: 1.69: 125 x 4