Mould within roof?

zomex

zomex

Member
Hello all,

My garden office I finished 3 years ago.

Was given a second hand window which now needs to be replaced (big mistake it leaked - leason learned).

I've exposed the ceiling/roof and noticed some black spots on the plywood. Is this mould? Would it be wise to increase the ventilation?

The roof is a cold roof, it's vented between the plywood and insulation. It feels very dry in the roof space, but if the black spots are mould it would suggest otherwise.

Walls are bone dry which I'm happy about.

Thanks
 

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zomex said:
Hello all,

My garden office I finished 3 years ago.

Was given a second hand window which now needs to be replaced (big mistake it leaked - leason learned).

I've exposed the ceiling/roof and noticed some black spots on the plywood. Is this mould? Would it be wise to increase the ventilation?

The roof is a cold roof, it's vented between the plywood and insulation. It feels very dry in the roof space, but if the black spots are mould it would suggest otherwise.

Walls are bone dry which I'm happy about.

Thanks
Click to expand...
Generally 50mm between roof and insulation. Did you fit a vapour barriers?
 
zomex said:
Hello all,

My garden office I finished 3 years ago.

Was given a second hand window which now needs to be replaced (big mistake it leaked - leason learned).

I've exposed the ceiling/roof and noticed some black spots on the plywood. Is this mould? Would it be wise to increase the ventilation?

The roof is a cold roof, it's vented between the plywood and insulation. It feels very dry in the roof space, but if the black spots are mould it would suggest otherwise.

Walls are bone dry which I'm happy about.

Thanks
Click to expand...


Looks the moisture didn't vent quickly enough after the leak.

Window replaced, if it's vented like you say and there's a breathable membrane in there, it should go back ok.

More info needed though.
 
Thanks for the replies.

I don't remember the window leaking on the side of the photos. The other side where I know it did leak has a lot less black spots. So it must have been leaking worse where I wasn't seeing it.

There is a vapour barrier on both the walls and ceiling. Walls are completely bone dry behind the vapour barrier. Plasterboard was slightly damp but I have 0 ventilation in the room itself as the window doesn't open. New window will open and also has vents built in. I'm hopeful this will control that.

Ceiling also feels dry. Perhaps as someone suggested it's not recovered since the leak? But that was a long time ago as I ended up covering the window with plastic to stop the leak. So it's not been leaking for over a year.

50mm ventilation gap in roof. Plus the furrings go in the opposite way to joists to give further ventilation.

I was given a lot of the stuff from a mate who had left overs from his garden room. This ended up being a mistake. For example the overhang has a plastic fit underneath (don't know the name of it). I cut and added some vents but I don't think it's enough. One option I've considered is replacing this with a fully vented one. I'll send a photo of what I mean today.
 
I'll get a better photo later.

If you zoom in under the roof hang you'll see a mix of 50mm lights and vents. I don't think the vents are enough and believe replacing this with a new fully vented one is going to be the way to go.

PS: Not a bad gate a cladding for a website guy
 

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zomex said:
Yeah I'm going to increase ventelation as much as I can including replacing the sofit with a full vented one.
Click to expand...

Looks like a nice job mate. Useful info tbf as I’m part way through building my own garden room with a cold roof. Was considering different options for the soffits.
 
ChrispyUK said:
Looks like a nice job mate. Useful info tbf as I’m part way through building my own garden room with a cold roof. Was considering different options for the soffits.
Click to expand...

Definitely recommend the fully vented one. Something like this:

www.plasticbuildingsupplies.com

Anthracite Dark Grey Vented Soffit Board

Our Anthracite UPVC Vented Soffit Board offers a modern solution for roofline ventilation and protection, combining functionality with an elegant dark grey finish. Featuring continuous air vents, this soffit board promotes consistent airflow to preve
www.plasticbuildingsupplies.com www.plasticbuildingsupplies.com

Also venting from both ends is recommended.

Best advice I can give is don't make the same mistake as me. Think about internal ventilation also. A window that can open or some sort of extractor vent. My plasterboard is damp because I didn't think about this until now.

Considering I've not got the ventilation right and had a leak I'd say it's held up pretty well over 3 years.

Also think about where you're going to hang things and put patress in. That's one thing I'm going to fix as part of this. I didn't think about this and had to fit a piece of plywood behind my radiator to hit the studs.
 
zomex said:
Definitely recommend the fully vented one. Something like this:

www.plasticbuildingsupplies.com

Anthracite Dark Grey Vented Soffit Board

Our Anthracite UPVC Vented Soffit Board offers a modern solution for roofline ventilation and protection, combining functionality with an elegant dark grey finish. Featuring continuous air vents, this soffit board promotes consistent airflow to preve
www.plasticbuildingsupplies.com www.plasticbuildingsupplies.com

Also venting from both ends is recommended.

Best advice I can give is don't make the same mistake as me. Think about internal ventilation also. A window that can open or some sort of extractor vent. My plasterboard is damp because I didn't think about this until now.

Considering I've not got the ventilation right and had a leak I'd say it's held up pretty well over 3 years.

Also think about where you're going to hang things and put patress in. That's one thing I'm going to fix as part of this. I didn't think about this and had to fit a piece of plywood behind my radiator to hit the studs.
Click to expand...

I’m fitting an opening window/windows and French doors, although that’s to be finalised. I’m going to line the internals with osb before PB.
 
ChrispyUK said:
I’m fitting an opening window/windows and French doors, although that’s to be finalised. I’m going to line the internals with osb before PB.
Click to expand...

Sounds like a nice job. Hope to see some photos

Lining with OSB first is a good move. If I had the funds and time again I'd do the same.

I did use 15mm soundboard though (ceiling fun by myself haha) so it's pretty solid. Currently working on the adding joists for the new window. Built the upstand already.
 
zomex said:
Sounds like a nice job. Hope to see some photos

Lining with OSB first is a good move. If I had the funds and time again I'd do the same.

I did use 15mm soundboard though (ceiling fun by myself haha) so it's pretty solid. Currently working on the adding joists for the new window. Built the upstand already.
Click to expand...

Yeah, they’re a bugger on your own.

I’m just waiting on ‘a lift’ to get the back wall up and into place, then it’s all systems go. I’ve made a flitch beam to go all the way across the front which I’ll also prop so I can get the roof on. Can then decide what windows and doors are going in.
 
Window progress going well.

Looks like it's £300 to patch my rubber roof or £500 to re-do the whole thing so I think I'll re do.

Wondering if I can pick anyones brains reading this.

1. I was planning or removing the old rubber, giving the plywood a slight sand and potentially SBR then re-do the roof.

2. Or another option more expensive is to go over the old plywood with a layer of OSB.

The rubber company don't think (or perhaps don't want to be liable) the glue is going to bond to the plywood/old glue so they suggested option 2.

Cheers
 
zomex said:
Window progress going well.

Looks like it's £300 to patch my rubber roof or £500 to re-do the whole thing so I think I'll re do.

Wondering if I can pick anyones brains reading this.

1. I was planning or removing the old rubber, giving the plywood a slight sand and potentially SBR then re-do the roof.

2. Or another option more expensive is to go over the old plywood with a layer of OSB.

The rubber company don't think (or perhaps don't want to be liable) the glue is going to bond to the plywood/old glue so they suggested option 2.

Cheers
Click to expand...

Probably safer. How many square metres?

I was weighing up rubber vs fibreglass for mine and as there is a big tree next door quite close think I’m going with fibreglass.
 
ChrispyUK said:
Probably safer. How many square metres?

I was weighing up rubber vs fibreglass for mine and as there is a big tree next door quite close think I’m going with fibreglass.
Click to expand...

About 14 (tiny office).

Will send some photos today. Will have the roof timbers done today. Just got to figure out a way to pack and repair where the furring strips were.

Ah I see. I think fibreglass is good from what I've seen and it can be repaired which is a bonus.
 
This is where I'm at now.

Upstand for window built. Structure for new window done and frame fitted.

Next step is to fill in with plywood to the new frame but going to be a pain as need to figure out fall with gaps.
 

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bobski said:
20 should be ok
But the dark colour can make them expand. They can creek and crack (noise) when the sun hits them.
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Thanks for the advice. I’ll look into a bit more. I did a grp flat roof for a friend a few years back so have a bit of experience and that went well but not quite as big as this.
 
Got the window frame finished. Used plastic shims to replicate the furrings fall.

Scarcthing my head about the roof. Not sure whether to patch existing rubber, replace with new rubber. Was also considering TPO as I have experience with heat welding.
 

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zomex said:
Got the window frame finished. Used plastic shims to replicate the furrings fall.

Scarcthing my head about the roof. Not sure whether to patch existing rubber, replace with new rubber. Was also considering TPO as I have experience with heat welding.
Click to expand...

Looking good

I’m always of the attitude that I don’t want to go back and redo something, even if it means a bit more pain and money.
 
Got a lift yesterday to get the back wall up.

Taking a few days off this week before starting next job, so hoping to get partial front walls done, side walls clad and roof timbers on. Will depend if I can get the flitch beam up though as prob on my own and it’s a weighty fooker.

Mould within roof?
 
Stud work is 4.8 x 3m internally. Will lose a bit with osb lining and pb, but still a good size and comes in under 15m2. Ordered a load of 5x2 C24 for the roof joists today and will be doubling up every other one. Selco have the 8x2 osb roofing sheets on offer so ordered those too. Hopefully get those on by Wed/Thurs and can sheet the roof off till the next session.

My little ‘work shop is about 5.5x4.5 feet so a step up (y)
 
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