Flat roof pitch

[gaz1]

my shed is based on what your wanting to do kim

smallest width has beams fitted and then firrings ontop with boards fitted



this dormer roof has the firrings fitted and you can just seem them fitted ontop of the beams



you can buy 3.4 firrings already cut for you but you will have a problem at the thin end near to the wall edge

my advice is to trim the end so you have an 1/2" to 1" thickness as you will need to fit trimmer woods outside of your wall this will allow you to fix to a solid part where your gutter fastens too

keep the cut offs they fit to the rear ontop of 3x2

if you do use full beams then your best coming over the wall so you can then fit the barge board and then your gutter onto it

like this 6" beams pref taking note you will need one as close to the wall as posible if not on your internal wall if doing a double wall build

 

[northwest]

Will save me so much head room with the plan I have for my garage.

Second Storey?

Won a local LBA award. Not that I got any of the credit.

I once won a major award, I organised the job, planned it and did 70% of the work. Never had a mention. Learned a great deal about politics though.

 

[KimB]

I looked earlier. Probably some on my pc but I'm on a newish phone.
Just straight cut decreasing in height.

If firings are spaced at 400c each
Stepped firring would be 5mm ish taller than the previous.


Counter battened firings are good for ventilation as they let air circulate between joists.

If your garage is long and narrow really should cut your joists across the shortest length not the long run.

I think I get what you mean now. And yes my joists will be across the shortest length because it’s 9m long probably should’ve clarified earlier. So I’ll probably look to do it 2x3 joists and then firrings on top.

 

[KimB]

Second Storey?



I once won a major award, I organised the job, planned it and did 70% of the work. Never had a mention. Learned a great deal about politics though.

Nope, little gantry crane
Isn’t that the truth as well

 

[eLuSiVeMiTe]

I think I get what you mean now. And yes my joists will be across the shortest length because it’s 9m long probably should’ve clarified earlier. So I’ll probably look to do it 2x3 joists and then firrings on top.

3x2 won't cut it. For a 4m span.


See here.
https://www.timberbeamcalculator.co.uk/span-table/flat-roof-joists?load=1.5&class=C16
That's for c16. Not sure if c24 changes the width.

I'd be looking for at least 2 rows of noggins. Thought I'd probably do 3

 

[Agroshield]

...the "minimum" would be 1/2" per 12", or round it off to 3 cm per 30 cm.

Your metric conversion has gone wrong somewhere.

1/2" per 12" is 1 in 24.

3 cm per 30 cm is 1 in 10, more than twice as steep.

 

[sako243]

@KimB when it actually comes to buying the wood I'd highly recommend giving the Mid Sussex Timber Company a call. I was up visiting @8ob last year and we were chatting about my workshop build and the difficulty I was having finding the 12x3 and 12x2s I wanted from the usual sawmills and culprits down here. He vaguely remembered they'd used a company that specialised in oversized timbers before and narrowed it down to MSTC. Phoned them up and they had them in stock and at an incredibly good price, the only real gauge I had was a local sawmill here who in the past have been very good on price could only supply ungraded 12x3s for 3x the price. It was beautifully dry and straight wood and all C16 and C24 to boot. What was going to be £3-4k worth of timber ended up being around the £1.2k so even if I hadn't have been up there with a trailer it was well worth a dedicated trip from very West Wales to collect it.

Absolutely no affiliation to them other than very happy customer - in fact some of the local guys here have subsequently been in touch with them as they're also struggling to find suitable timber locally.

 

[Arc Tourist]

.................................... or round it off to 3 cm per 30 cm.

Your metric conversion has gone wrong somewhere.

1/2" per 12" is 1 in 24.

3 cm per 30 cm is 1 in 10, more than twice as steep.

Notice I said, " round it off ". Makes metric calculations easier, and a bit more slope would be beneficial compared to a little less.

 

[eLuSiVeMiTe]

Notice I said, " round it off ". Makes metric calculations easier, and a bit more slope would be beneficial compared to a little less.

Even at 1:40
Every 400mm it will only rise 10mm

Though I agree. If you can stand it a greater fall won't do any harm.

 

[Arc Tourist]

Yeah, and the difference between 1 in 24 and 1 in 10 is only an additional drop of "less" than one inch (25mm) over the span of Kim's proposed three and a half metres. And as you say, more is better.

 

[gaz1]

I think I get what you mean now. And yes my joists will be across the shortest length because it’s 9m long probably should’ve clarified earlier. So I’ll probably look to do it 2x3 joists and then firrings on top.

kim are you planning a long roof at 9m to the gutter? as it would be best fitting the gutter at the side of the garage the smaller width

 

[KimB]

kim are you planning a long roof at 9m to the gutter? as it would be best fitting the gutter at the side of the garage the smaller width

No I’m planning a garage to have a gutter along the longer length ie so it slopes from the 3.5m width. Not the 9m length.

 

[gaz1]

then just use the beams lifted at one end 5" to 6" beams will be adequate for your needs 6" being the better beam to use

also you can fit 4" roll of insulation as well but if you want 6" insulation you will need 7" beams

build your block walls as normal fit 2 4x2s at front and one 4x2 wall plate woods at rear this will give you your fall that you need

you can then fasten down your beams to it at front and rear and then fit l plates to your wall plates to hold your roof down

plastic fascia for front and rear no fascia wood needed and it looks like this



also if you buy in the 9mm or the 11mm osb board and you have your wall plates fitted

if you fit 2 2x1s to your wall plates with a space for the osb board either wall side you only have to screw up the middle part with 2 screws at the beam

therefore only the middle will need to be filled this means that you can fit insulation in your roof before you fit your roof boards go on your roof weather dependant of coarse

this means you can stop thermal bridging at your ends as your insulation will be over the wall plates

just easier to fit from above than below and also cut to length

or as i have done blocks against the wall on the plate at middle x2 has the 11mm gap screw through 3x2 at beams and move onto next board screw up after the roof has been insulated and boards have been fitted its just a speed reference to get it insulated and roof on asap due to the weather

 

[mtt.tr]

Is you don't care about a flat ceiling just riase one wall plate

 

[brightspark]

thats a ski slope

 

[KimB]

Another question or two if I may.
firstly, what should the projection be over the walls? So the garage itself is 3.25m x 9m should it be like 200mm or something?

Secondly, any recommendations where I can get a EPDM and probably the fascia for it as well? I’d probably order it from the same place.

 

[mtt.tr]

Another question or two if I may.
firstly, what should the projection be over the walls? So the garage itself is 3.25m x 9m should it be like 200mm or something?

Secondly, any recommendations where I can get a EPDM and probably the fascia for it as well? I’d probably order it from the same place.

Depends what you want, i normally have 150 but you can have deep overhangs just the construction changes if the over hang wraps around.

These are both 500 Overhangs, mostly people ladder the corners but the feel crap.

 

[Agroshield]

firstly, what should the projection be over the walls?

What is the function of the space adjacent to and below the overhang? What you can or want to do with that can guide your decision.

If you need a vehicle or anything high to pass, then a big overhang might not be best. You have to add gutter width to overall outwards projection and consider downpipe route in vertical clearance.

If just a pedestrian route, then a larger overhang might be a sheltered walkway if you need to go from A to B in the rain.

 

[MysterG]

Another question or two if I may.
firstly, what should the projection be over the walls? So the garage itself is 3.25m x 9m should it be like 200mm or something?

Secondly, any recommendations where I can get a EPDM and probably the fascia for it as well? I’d probably order it from the same place.

I've used used these people Rubber4Roofs 3 times for EPDM, utilising their online calculators. Never had an issue. I've always just used treated/painted timber for fascias.

First time I used it was a small dormer.

 

[gaz1]

also depends on whats going on your walls as well as what your wanting

if your cladding it then its got to come out more from the wall, a straight brick wall like above its down to owners choice

50mm/100mm soffit vent upwards

Coroline Corrugated Roof Sheets, Dry Verge, Roof Ventilation & More

Coroline Corrugated Roof Sheets, Polycarbonate Roof Sheets & More. All Your Roofing Ventilation Needs Including Tile Vents, Soffit Vents & Fascia Vent...

www.roofingventilation.co.uk

White Vented Soffit Boards | DirectPlastics.com

Ventilate your roofline with white vented soffit boards from DirectPlastics.com Available on our online shop at a great price, buy today!

www.directplastics.com

Black Ash uPVC Vented Soffit | DirectPlastics.com

Manufactured by Homeline the Black Vented Soffit Board is available in a range of widths at DirectPlastis.com. Order online for fast UK delivery and low prices.

www.directplastics.com

then its your fascia board

White Glazing Bars, Trims & Accessories

White Glazing Bars, Trims, and Accessories offer a classic and versatile solution for the installation and finishing of polycarbonate roofing systems, conservatories, and various glazed structures.

www.plasticbuildingsupplies.com

Anthracite Grey Cap-Over Fascia 175mm | uPVC Fascias | DirectPlastics.com

The 175mm Anthracite Grey Cap-Over Fascia is an ideal solution for revamping a property's roofline. Order online from DirectPlastics.com for RAL 7016 Reveal Liner today!

www.directplastics.com

thicker board is better

White Fascia Board | 5M x 200mm x 18mm | Replacement Fascia

5M x 200mm x 18mm full replacement fascia board in white, are used to replace the existing wooden fascia or on a new build installation. The guttering is then fastened onto the fascia boards.

www.cabp.co.uk

4"-5" gutter bracket rough size of them for the gutter