Installation of PV on Corrugated Asbestos Roof ??

[Adokforme]

Many thanks for your responses and links Guys. It all suggests there are at least options and not simply a no go.
It's a commercial property my son and his partner are interested in to run their business from following several years of leasing a prenises they have really outgrown. The roof in question appears to have steel joists and pirlins, still to be confirmed, as the entire inside is coated with a sprayed foam insulation!
Presumably it is reasonably sealed from within at least!
The option of removing it all centres around a cost with figures circa £50 sq metre for disposal, so possibly greater than the actual cost of a new roof itself!
I appreciate your replies as it keeps their interest alive which may eventually lead to them putting in a bid.
I'll keep you posted if so.

[Oliver90owner]

The sprayed foam may be a greater risk than the cement/asbestos roofing sheets. Be careful!

[Stinsy]

Assuming the kids are buying the freehold then if I were them I’d have the asbestos removed and have a new, insulated roof installed on the building (of course including solar).

The hysteria surrounding asbestos isn’t going anywhere, the building will be worth more and it’ll be easier to borrow against it in future if there is no asbestos.

[Thebeeman]

Surely the asbestos roof is a reason for a large reduction in the purchase price, at least equal to the removal/disposal cost.
A quote from a reliable legal contractor for the work would help in negotiations.

[spread-tee]

The spray foam does complicate the issue quite a lot, it will be a struggle to dismantle the roof without doing considerable damage to the sheets which increases the risk considerably. I concur with Beeman, get some quotes for the work before you buy. If you feel unsure about the outcome personally I would walk away.

Desp

[jonc_uk]

Surely the asbestos roof is a reason for a large reduction in the purchase price, at least equal to the removal/disposal cost.
A quote from a reliable legal contractor for the work would help in negotiations.

I think this thread is being conducted without a view of the industrial / warehouse market. Since covid there has been a shift in demand for commercial warehouse and office space - office has gone down, warehouse up.

In my area there is huge demand and little supply. Hence the limited ability to negotiate. I still maintain that an asbestos roof, encapsulated within a metal one is not a problem. You need an asbestos register and a risk assesment if you are working with it but these are standard things. A spray foamed roof is even less of a problem. My industrial estate was constructed at a time when it was the de facto roofing material. No one is removing it - they are all being over-clad when required.

[Gareth J]

We used to do lots of fibre cement roofs, with either steel of timber purlins. We just used to drill them , K2 do good mounting bolts for both timber and steel purlins, K2 call them hanger bolts.
You could reuse the existing holes in the sheeting if you were worried.

Can I ask for your wisdom on this topic?

Am currently pricing up a solar setup for a timber purlined roof with cement fibre sheets. They'll be brand new sheets but old purlins, so a bit of sag but not necessarily any worse than new ones. Expecting to use K2 kit.

What I'm thinking of doing is, using the hanger bolts you mentioned, attach rails up and down the roof, so, perpendicular to the purlins, and bolt panels in landscape orientation, directly to these rails. A pair of rails per "column" of panels.

However, we've a set of panels here installed on a cement fibre roof by an MCS outfit that used vertical rails, then crossed those rails with horizontal rails and put panels on portrait.

Will just using a single set of rails be too risky? The old purlins should be pretty stable now and not sag much more but I can see that bracing in both directions will add a lot of rigidity.

Hopefully this isn't too off topic for the original post, and may even be helpful

[Petertc]

I am trying to remember what we did, it's more to do with the clamping area on the panels. If this is able to fit within the purlins spacings, then you should be able to go horizontal rails with portrait modules, or go vertical rails with landscape panels.

Best thing to do is setup as a user on the web app K2 base, as you can put in your location, height above sea level and type of roof , modules and it will tell you what spacings you can use and if you need to double rail. The app will also give you a full list of materials required.

[Gareth J]

I am trying to remember what we did, it's more to do with the clamping area on the panels. If this is able to fit within the purlins spacings, then you should be able to go horizontal rails with portrait modules, or go vertical rails with landscape panels.

Best thing to do is setup as a user on the web app K2 base, as you can put in your location, height above sea level and type of roof , modules and it will tell you what spacings you can use and if you need to double rail. The app will also give you a full list of materials required.

Thanks, yea, I already have a K2 account and have a few layouts am playing with. Although, I must have something wrong with the windspeed number as it tried to put about x8 rails per panel to start with. There are a few similar setups nearby to copy/inspire. But if I can get away without crossing the rails, I will.

[Swwils]

Why are you improving the value of a building you don't own? You'll just pay more rent for your own improvements at the very best