Shed build, many many questions...

[Torx]

Right, didn't want an apex roof anyway, didn't lose much height.

Any comments on stud layout before I go on? Family for scale:

Centre lines represent 8' x 4' sheets, hence the slightly odd stud spacing with some needed to overlap the sheets.

No idea what I'm doing, if you haven't noticed yet.

Also, I acquired another window.

 

[Jameshow]

Do you really need 3 studs either side of the doors / windows?

1/2 would be fine?

 

[Torx]

Do you really need 3 studs either side of the doors / windows?

1/2 would be fine?

I wondered that too, thanks, I'll lose one.

 

[Fitzroy]

Why is your wife wearing a bikini in your shed and you need to install a toilet as your daughter is bursting! I like the wide high window design.

My shed is a similar design and on the rear and side walls where I had no windows I used 600mm spacing, plenty strong enough. On the front and side with windows it made little odds to the number of timbers as the design to incorporate the windows and door drove the stud arrangement.

My roof span is 3.2m and I used 6x2s in the roof, this is also to enable a cold roof design, with 100mm insulation and a vented 50mm air gap above.

Personally I'd steer clear of torch on felt. I've had plenty of sheds over the years with felt and it is not as durable as the EPDM on my current shed. Installing a single sheet with no joints is such an easy and quick way to get the building watertight. If you had upstands and internal corners it's a different beast but a big flat pent roof is crying out for it.

F.

 

[Torx]

Why is your wife wearing a bikini in your shed and you need to install a toilet as your daughter is bursting! I like the wide high window design.

My shed is a similar design and on the rear and side walls where I had no windows I used 600mm spacing, plenty strong enough. On the front and side with windows it made little odds to the number of timbers as the design to incorporate the windows and door drove the stud arrangement.

My roof span is 3.2m and I used 6x2s in the roof, this is also to enable a cold roof design, with 100mm insulation and a vented 50mm air gap above.

Personally I'd steer clear of torch on felt. I've had plenty of sheds over the years with felt and it is not as durable as the EPDM on my current shed. Installing a single sheet with no joints is such an easy and quick way to get the building watertight. If you had upstands and internal corners it's a different beast but a big flat pent roof is crying out for it.

F.

It does seem to make a lot of sense, but why don’t commercial roofers seem to like it? Perhaps they like coming back to re-do felt roofs every 5 years?

 

[Jameshow]

Same reason hair dressers only take a little off!!

 

[Torx]

Without the additional studs around the doors / windows, the biggest spacing between centres is 554mm, worth having another here, or are the double studs either side adequate anyway?

 

[Torx]

Why is your wife wearing a bikini in your shed

It is a bit of a distraction at times, if I'm honest. I've been thinking about having a word.

 

[Molynoox]

looks good
a small comment on stud spacings - you have optimised for imperial sheets, this means if you plasterboard the inside (which is metric) all your sheets will fall slightly short of the stud and you will get a lot of waste. PB is very cheap so not a huge issue, but the cuts do take time.
only real way to avoid that is using metric sheathing but that is quite rare (restricted to I think 11mm OSB only)
you may not be doing plasterboard on inside, in which case you can just ignore.

Martin

 

[Torx]

looks good
a small comment on stud spacings - you have optimised for imperial sheets, this means if you plasterboard the inside (which is metric) all your sheets will fall slightly short of the stud and you will get a lot of waste. PB is very cheap so not a huge issue, but the cuts do take time.
only real way to avoid that is using metric sheathing but that is quite rare (restricted to I think 11mm OSB only)
you may not be doing plasterboard on inside, in which case you can just ignore.

Martin

Good point, definitely something to bear in mind for the next one which will be more of an office space, but this one is just a shed / workshop extension so I'm thankful I don't have to worry about that!

 

[Torx]

Side question:

Can anyone explain (in laymans terms), why felt / rubber etc., are suitable for low pitch roofing but (seemingly impermeable) sheet steel is not? I can't quite get my head around this, I must be missing something obvious - wind?

 

[Jameshow]

Side question:

Can anyone explain (in laymans terms), why felt / rubber etc., are suitable for low pitch roofing but (seemingly impermeable) sheet steel is not? I can't quite get my head around this, I must be missing something obvious - wind?

Most people aren't conversant with metal roofing. I think it's better in every way.

Obviously it need to be corrugated.

All you need is a small angle grinder and the right screws.

 

[Jones]

Low pitch roofs will often have standing water caused by debris dams or movement in the underlying structure such as timber shrinkage, bowing or just temperature movements. Even though the fixings for metal roofing have gaskets this can cause leaks, also corrosion of metals and coatings will occur if puddles form. So metal roofing must have enough fall so there's no risk of puddling or debris build up causing permanently damp areas . EPDM can be used as a swimming pool liner, sometimes inadvertantly when internal downpipes get blocked.

 

[Fitzroy]

Side question:

Can anyone explain (in laymans terms), why felt / rubber etc., are suitable for low pitch roofing but (seemingly impermeable) sheet steel is not? I can't quite get my head around this, I must be missing something obvious - wind?

My outhouse had a shallow roof that had corrugated iron on it, the wind would blow the water back up the roof and it would leak at the head end, where it was tucked under the tiles. A terrible design which the EPDM replacement didn't solve in being EPDM, but it did allow me to create an upstand under the slates with the EPDM formed over the top.

 

[Torx]

Low pitch roofs will often have standing water caused by debris dams or movement in the underlying structure such as timber shrinkage, bowing or just temperature movements. Even though the fixings for metal roofing have gaskets this can cause leaks, also corrosion of metals and coatings will occur if puddles form. So metal roofing must have enough fall so there's no risk of puddling or debris build up causing permanently damp areas . EPDM can be used as a swimming pool liner, sometimes inadvertantly when internal downpipes get blocked.

Ah, that makes sense, I didn’t consider the fixings. I do like the idea of metal roofing but I think condensation might also be a problem (if it’s not done right).

 

[Molynoox]

I have nothing against the metal roof sheets, but condensation would be my biggest concern with them also.

Because of the shape of the sheets (i.e. not flat), you can't easily push the insulation tight up against it to close off the air gap next to the cold metal (which is where the condensate will form). Especially if using non compressible insulation like PIR because it wont fit to the curves of the sheet.
If you want metal, the kinspan panels are a nice way around that as the PIR is moulded 'inside' the sheets in the factory, thus reducing the problematic air gap to zero.

My current thoughts / preference on roofing options for flat roof sheds, in order of preference:

1. sedum over EPDM (expensive and needs stronger roof=thicker joists/or metalwork=less head height/or even more cost if sticking to 2.5m)
2. artificial grass over EPDM (100% waterproof, looks nicer than EPDM arguably, not sure on the grass maintenance?)
3. EPDM (looks 'OK', lasts for 30 years, 100% waterproof and maintenance free, quickly makes building waterproof)
4. kingspan panels (look a bit industrial, strong /can do big spans, easy and fast to assemble, 100% waterproof and maintenance free)
5. felt (doesn't last well, doesn't look good, but gets the job done and is cheap, in short term anyway)
6. metal sheeting (industrial look, potential condensate problem, not always waterproof, not always maintenance free)

GRP should be in there but I don't know enough about it other than it looks complex, messy, weather dependant, specialist etc

All in my opinion only

Martin

 

[Torx]

I have nothing against the metal roof sheets, but condensation would be my biggest concern with them also.

Because of the shape of the sheets (i.e. not flat), you can't easily push the insulation tight up against it to close off the air gap next to the cold metal (which is where the condensate will form). Especially if using non compressible insulation like PIR because it wont fit to the curves of the sheet.
If you want metal, the kinspan panels are a nice way around that as the PIR is moulded 'inside' the sheets in the factory, thus reducing the problematic air gap to zero.

My current thoughts / preference on roofing options for flat roof sheds, in order of preference:

1. sedum over EPDM (expensive and needs stronger roof=thicker joists/or metalwork=less head height/or even more cost if sticking to 2.5m)
2. artificial grass over EPDM (100% waterproof, looks nicer than EPDM arguably, not sure on the grass maintenance?)
3. EPDM (looks 'OK', lasts for 30 years, 100% waterproof and maintenance free, quickly makes building waterproof)
4. kingspan panels (look a bit industrial, strong /can do big spans, easy and fast to assemble, 100% waterproof and maintenance free)
5. felt (doesn't last well, doesn't look good, but gets the job done and is cheap, in short term anyway)
6. metal sheeting (industrial look, potential condensate problem, not always waterproof, not always maintenance free)

GRP should be in there but I don't know enough about it other than it looks complex, messy, weather dependant, specialist etc

All in my opinion only

Martin

I like the idea of a sedum roof, maybe next time. Most of the metal roofing materials (including the kingspan, I think) do require a much greater pitch, so out of the question for this.

How does the rubber hold up in extreme temperatures like we’ve experienced recently?

 

[Torx]

@Fitzroy did you fit these things (gutter trim) on the EPDM roof?

Just wondering what I should allow for them in the height, looks like about 20mm?

 

[Torx]

@Fitzroy did you fit these things (gutter trim) on the EPDM roof?

View attachment 141892

Just wondering what I should allow for them in the height, looks like about 20mm?

Ah ha

Found a good site for this stuff - Rubber Roofing Systems, EPDM Rubber Roofs & Materials | Rubber4Roofs

 

[Torx]

Doors.

I've been considering buying one of these...

https://www.leaderdoors.co.uk/lpd-d...inished-framed-ledged-braced-door-rflb-p55742
....as they're cheap and relatively solid (I've had one on my garage for 3 years and only treated once, and it's been fine so far...) then clad over it with whatever I decide on.

The door height at the moment is 1900ish.

This is mainly out of laziness, just to get a door on it quickly.

Any comments?