Is it possible/cost effective to insulate a prefab garage to use as a workshop?

Section62

https://forums.moneysavingexpert.com/discussion/comment/81962204#Comment_81962204

There's a picture on page 1 - steel frame with (asbestos?) cement board.

KBM68

So,I just found out the garage isnt post 2000 as I was told so it is likely to be asbestos which really pisses me off

I dont mind (much) that its asbestos, I do mind that I was misled

So im thinking, assuming the walls are ok, remove the roof (pay an expert), replace the roof - adding i the insulation needed, (pay an expert)

!!!!!!

WIAWSNB

https://forums.moneysavingexpert.com/discussion/comment/81963604#Comment_81963604

Replacing the roof is clearly the most reassuring option, and box-section steel roofing would also improve the aesthetics of the building.

But, provided the roof is in good condition, and it appears to be, there is infinitesimal risk to health provided the sheets remain intact.

If you wanted to be doubly sure, you could load up a paint sprayer with, say, SBR, don a darned good mask, erect your scaff tower, and coat the inside surface of the sheeting. It ain't necessary, but if you are getting a small scaffold tower for this job in any case, and you probably should, then it's a relatively small task - you could even brush it on… That will seal the surface, and hopefully provide additional reassurance.

If the roof is in good condition, I'd personally keep it. Perhaps get quotes, and then decide?

Then, personally, I'd look to either construct a timber frame sitting on that lower steel horizontal tie, on to which rigid insulation could be attached, and then a lightweight finish of your choice - say thin PVC T&G cladding - could be adhered, or else go cable-suspended. I haven't done this, but image it would involve a series of cables attached to the A-frames and hanging down. These would pass through, or attach to, rigid insulation sheets of, say, 3" thickness, and 'tensioned' to get things level. Sheets foamed and taped where they join. Then adhere the finish of your choice to the underside as before. (Not sure how the wind might affect this!)

With the cable method, it should be just as easy to have this ceiling at a higher level if wished, say a foot or so above the horizontal tie, to create a part-vaulted ceiling if you wanted the feeling of more space. The timber frame method could also be done this way.

With either option, the idea is to completely isolate the roof space above from the living area - that upper loft should be left fully ventilated via gaps in the eaves and ridge. You would, of course, add a couple of inspection hatches.

teaselMay

Yep what WIAWSNB said. I had the opposite in my old rented house, spent a decade thinking the shed roof was asbestos (as did my landlord) and periodically vaguely checking its integrity and being careful not to disturb it. Only when a storm tried to take the roof off did I discover it definitely wasn't asbestos because it had been replaced by the previous owner and current neighbours (our sheds were semidetached).

You could still just keep it as it is if it's in good condition. If the current owners have misled you you could ask them to drop the price by the cost of replacing the roof.

Remember the need for ventilation in that loft space (i am a broken record)

KBM68

I know ventilation is important

I was in a house once with black mould, so i installed a positive flow ventilation system which fixed it all with a few weeks

Ectophile

https://forums.moneysavingexpert.com/discussion/comment/81962238#Comment_81962238

Why didn't I see that previously? Oh well. In that case it's hooks/wires/clamps to fit a false ceiling, like in many offices.

WIAWSNB

I wonder how far apart the steel A-frames are? Looks as tho' it could be only around 1m?

If so, I'd now be more inclined to support the ceiling using a timber framework, say 3x2 CLS, rather than potentially tricky cables.

The steels look to be angle-profile - 'L' - so a dead simple starting point could be to adhere (Gorilla polyurethane, or Stixall) treated 2x2 timbers to the L-internals where needed, Ie as far up from the bottom as you want the ceiling to be, and then the CLS frame for holding the actual insulation panels will be screwed to this. No drilling into metal required.

Lawdie, I'm loving this project... 😢

Bigphil1474

OP, just to say that if the roof is cement panelling containing asbestos, you don't need a licensed asbestos company to remove it, you will need a company that will remove it properly and dispose of it properly of course. A job like that would be classed as unlicensed work so anyone can do it. They should remove it in complete panels and treat accordingly. Agree with WIAWSNB though, worth considering keeping it.

Section62

https://forums.moneysavingexpert.com/discussion/comment/81964982#Comment_81964982

You're suggesting glueing bits of wood to the steel trusses and then hanging the weight of a timber frame and ceiling panels off those?

If so, that would be dangerous. There would need to be mechanical fixings (bolts/screws/clamps) between the timber frame and the steel trusses.

And moreover, the trusses are unlikely to have been designed to take vertical loads on the tie members (bottom chord) - the roof is a minimalist design likely intended to take the load of (wet) roofing sheets plus snow/wind loading above, hanging a relatively heavy structure off that in order to make the space 'liveable' is potentially lethal, and not a DIY project.

I know folk mean well, and this is a money-saving site, but some of the advice in this thread is worryingly poor. Hopefully if the OP buys the property they will get a professional in to advise on a way to achieve what they want, safely and energy efficiently.

WIAWSNB

It's a vaulted ceiling - it would have nowhere to go :-)

Seriously, these A-frames, which are currently holding at least 500kg of corrugated cement sheet in gale-force winds, ain't going to handle some CLS and Kingspan?

Pffft.

And, if you ensure the metal surface is clean, a Stixall'd length of rough timber is not going to be pulled off. I have tried - the wood split.

But, fair do's - it has to be KMB's considered call, and he should investigate further. All I'll add is, I know what I would do, and I know it would work.