Insulating workshop roof. Spray foam. Thughts?

[bricol]

The company that did spray foam in my dads house swore it would seal the old tiles, stop them leaking, stop them blowing off, and gave a 30 years guarantee.... except after he died and we came to sell the house the company didn't exist any more....

We had to get a roof specialist to come in and say there was nothing wrong with the foam etc, before the sale could proceed.

I'm about to have exactly that experience with my mum's house . . .

As well as the PVC over-cladding on the timber front and back, soffits etc - which I reckon has probably guided 30 yrs of moisture inside . . .

 

[tom2207]

Leaks you dont fix , dont ever get any better .

Fix the leaks is issue 1 .

Then when its dry at least you can sit in there and have a think about insulation.

 

[knighty]

have you priced up for a new roof ontop?

it was a few years back before prices went up but a mate of mine ran battens along the roof, unrolled insulation between them then a new roof on top

it was surprisingly cheap, fixed his leaks and keeps the place warm too

new roof sheets were full length, so no joins in the middle - make them quick and easy to put up


just don't stand on a sky light fall through and land on your head like I did and you'll be fine :-)

 

[Erie Fred]

spray foam will burn

That's a funny looking outlet on that test wall......

 

[gaz1]

I'm about to have exactly that experience with my mum's house . . .

As well as the PVC over-cladding on the timber front and back, soffits etc - which I reckon has probably guided 30 yrs of moisture inside . . .

Spray foam roof insulation.

My sisters and I are in the process of selling my dads old house, all was going well, but Friday the estate agent told me the buyers lender had mentioned they had some issue with the above roof insulation. It was done many years ago, and Google tells me horror stories about it making houses...

www.mig-welding.co.uk

ive already prementioned metal c channel or metal z purlins as there a light cheap option for the roof structure interenal and not as heavy as wood

price for price they are both roughly same price

he has a 5" gap between the purlins of the roof

rogers previous pics of workshop envy

https://www.mig-welding.co.uk/forum/threads/fantasy-workshop.127567/page-2

 

[Blobber]

Numerous "professionals" had been up on this one over the years slathering allsorts on the joints, never worked just made it worse, in the end I did the skin over type roof, pretty easy once you get the track down and a telehandler to lift the sheets up, do it once, do it right

 

[Roger440]

Have you looked at overpainting the outside with bitumen paint, like blackjack?

It sort of finds and seals small holes.

Used it quite a bit over the years on various wriggly tin roofs that have got ‘tired’ around the nails. I have a pot waiting to go on here.

You won’t get the insulation of foam but none of the grief either.

Just thoughts…..

Ive got to insulate. But whatever method, i need to stop water getting in first.

The consensus is that.

 

[Roger440]

A quick fix for split sheets is to cut a valley (or two/three/whatever is required) from a skylight sheet and tuck them over the next lower sheet to move the water downhill. Done without going onto the roof and effective.

How does battoning over the purlins and sheeting compare cost-wise? Plasterboard would be cheapest?

The airgap will help a lot with heat retention, even with no actual insulation. Though you could tuck rockwool above.

Don't go onto the roof without either crawling boards that span X3 purlins. Or nets underneath. I know it's fairly new but it's a long way down. Seriously, don't.

Ive looed at all that. Including rockwall and a membrane rather than plasterboard or similar to keep weight down. These all involve workg 5 = meters up with "large" sheets of stuff. Really, really not keen on that. Proability of an accident, high. Still circa 5-6k of materials and i still have to do it all. For those reasons ive canned that idea.

Though id still have to fix the leaks. Wet rockwool will soon be on the ground.

 

[Roger440]

Could you live with the leak and build a shed within the main shed to protect things that are environmentally sensitive.

As per previous reply, to high up with big bits of sheet, steel etc.

 

[Roger440]

CT1 over the cracks.

This seems popular. But will it last? And for how long. UV is a bugger.

 

[Roger440]

have you priced up for a new roof ontop?

it was a few years back before prices went up but a mate of mine ran battens along the roof, unrolled insulation between them then a new roof on top

it was surprisingly cheap, fixed his leaks and keeps the place warm too

new roof sheets were full length, so no joins in the middle - make them quick and easy to put up


just don't stand on a sky light fall through and land on your head like I did and you'll be fine :-)

I found it surprisngly expensive. As per previous post it was circa £30K v £40, for a proper new composte steel roof.

Having measured it all today, the actual total roof area is 4000sq/ft. But 1700 of that isnt the area id insulate from the inside. The rest is a massive canopy and the area over office, kitchen etc.

So from inside its a bit over 2000sqft, v 4000 if doing outside. Yes, i could just over roof the workshop part, and if i couldt see it from the house, id be less concerned, but doing half would look truly ****!

Over roofing isnt a job id be prepared to take on myself, hence the costs. That an all inclusive price.

 

[Brad93]

They have specified classE fire retatdant foam.

But its only the roof, noit walls. And it over 5 mtrs up.

Most if not all grinding will be in an enclosed roof for the purpose.

Numerous "professionals" had been up on this one over the years slathering allsorts on the joints, never worked just made it worse, in the end I did the skin over type roof, pretty easy once you get the track down and a telehandler to lift the sheets up, do it once, do it right
View attachment 403598
View attachment 403599

On a system like that what's stops condensation/moisture from saturating the rock wool? or is there a air gap im not seeing?

 

[JOEPRO]

I need to insulate the roof of my workshop.

Its a touch over 2000 sq/ft. Roof of Fibre cement board on steel frame and purlins.

Ive looked at every concievable option.

Surprisingly, spray foam came in much better than i thought. With the advantage that i dont need to do it.

However. The roof has some minor leaks. In normal conditions, it doesnt, but today we had a moonsoon. And 4 monor leaks. 2 are clealy cracks in the panel, 2 are weeping around the sceews.

All the spray foam peole will tell you, it fine, it will seal it up. But is it? Really?

Anyone have an experience of this in a commercial building setting or similar.

Pic of roof

View attachment 403554

What year was the shed built approx?

Are you certain the roof is cement based and not asbestos containing sheets?

 

[Roger440]

What year was the shed built approx?

Are you certain the roof is cement based and not asbestos containing sheets?

2001. So pretty certain.

 

[Roger440]

On a system like that what's stops condensation/moisture from saturating the rock wool? or is there a air gap im not seeing?

Or, for me, more of a concern, a leak. You would never know. And wet rockwool is no insulator at all. See loads of new buildiungs going up with this system. They even install it when its raining which seems like madness to me!

 

[Onoff]

This seems popular. But will it last? And for how long. UV is a bugger.

It's supposed to be UV resistant. I rate the stuff. Used it on many a gutter. The white though goes yellow after time so if you want white use BT1.

I've actually done "the test". Fill a disposable cup with water. Slash it with a Stanley, water pours out of the cut. Run CT1 over the wet crack...it's sealed. The best bit comes next. Refill the cup. Slash it the other side. Run CT1 over the slash but from INSIDE the cup i.e with the nozzle underwater, it's sealed!

It's no good for sealing heating oil tanks though!

 

[Roger440]

It's supposed to be UV resistant. I rate the stuff. Used it on many a gutter. The white though goes yellow after time so if you want white use BT1.

I've actually done "the test". Fill a disposable cup with water. Slash it with a Stanley, water pours out of the cut. Run CT1 over the wet crack...it's sealed. The best bit comes next. Refill the cup. Slash it the other side. Run CT1 over the slash but from INSIDE the cup i.e with the nozzle underwater, it's sealed!

It's no good for sealing heating oil tanks though!

Thats good info.

Ref the oil tanks, Belzona. Assumimng you can still get it. We used to repair diesel tanks with it while they were still full!

 

[Onoff]

The CT1 rep is a really nice guy too, Kevin Cashin. Helped me out a few times with questions.

 

[Onoff]

Thats good info.

Ref the oil tanks, Belzona. Assumimng you can still get it. We used to repair diesel tanks with it while they were still full!

I did have some success with either Evo-Stik Sticks Like **** or The Dogs B@ll@cks Clear...can't remember which.

 

[Blobber]

Or, for me, more of a concern, a leak. You would never know. And wet rockwool is no insulator at all. See loads of new buildiungs going up with this system. They even install it when its raining which seems like madness to me!

But you would be happy to slather it all in expanded foam, how are you going to see any leaks? if it does leak its just going to rot the encased steel, especially the fixings for the sheets
Rockwool doesn't absorb moisture