New Roof for workshop

[Keith 66]

Time to ask the font of all knowledge fo advice!, My workshop is a standard Concrete double garage that has had its back wall shoved out a bit to increase size to approx 35 sqm. The roof is the standard old asbestos cement corrugated panels. The roof is now 45 years old & is in a state, couple of cracked panels garmed up with mastic to stop it leaking.
Im wondering what the best way to re roof it properly is going to be. Pitch is fairly shallow.
I want to insulate it as well
I will be taking the oportunity to put a full width lifting beam in while the roof is off, be silly not to!
Any ideas as to materials?

 

[addjunkie]

Firstly getting rid of the asbestos....some concils will remove it for free from a garage.

Id use insulated metal roofing either corrugated or box profile, but its pricey.

For cheaper just use fibre cement roofing sheets in 3 inch profile. Though 6 is cheaper.

You could board the roof and use an onduline type product, but fibre cement is about the same price and will out last you.

 

[8ob]

Another vote for the insulated roofing sheets, the steel trusses/structure of these concrete garages dont really lend themselves to adding insulation on the inside as an afterthought. The insulated sheets are a no brainer, often available S/H on the bay of thieves.

Bob

 

[gaz1]

the problem is getting rid of the old sheets

either reuse them or remove them there can be a cost to get rid of them

dont forget you can insulate above and below those sheets by using a false roof

 

[Keith 66]

We have checked regarding removal, council will take 40kgs of asbestos cement free above that it will cost. Fortunately i know the bloke in charge of refuse & recycling, wont get it free but getting a price will be easier! Im going to have to replace the purlins anyway as there is woodworm in some of them. Leaning towards the insulated steel at the moment.

 

[maz0]

The asbestos might be a problem, I was told I had to have some special firm come out and deal with mine and it would be X amount of thousands...and on the other hand I was told to just wait for a rainy day and take it apart using a hand-saw and respirator, making sure it was properly soaked, with a garden hose if necessary, black bagging as a I went, but only because mine was white asbestos, if it was blue then it would be a whole other story. In the end I didn't have to do either and sold the property.

 

[Burdekin]

Part of my workshop is the same asbestos roof, previous owner fitted metal roof straight over the top. No issues with condensation but I've now fitted a ceiling with insulation between.

 

[rcx132]

I really like the firbe cement sheets, the ones that USED TO contain asbestos. They work out really cheaper, cheaper than the crummy Wickes tar panels, they are rigid and self supporting so you don't need as many cross beams, and they can operate at shallow angles. And they blend into the environment. And strong enough to walk on (gently).

 

[awemawson]

The trouble with the Onduline sheets is they only come in 2 metre lengths, making overlaps necessary usually. I've an open fronted store that I roofed in Ondline 11 years ago, and it is still sound apart from one patch where a tree pressed onto it. Usually best to board first. It abuts a Portakabin that I am re-roofing so I had to remove the damaged sheets anyway for access. I'm having galvanised corrugated steel curved (like a pig ark but shallower) to re-roof the Portakabin

 

[rtcosic]

Another vote for insulated roofing sheets, such as:

https://www.panelsell.co.uk/insulated-panels-stock-articles?source=google&medum=adwords&campaign=741778453&adgroup=39159174899&keyword=kingspan seconds&matchtype=e&adposition=1t2&device=c&gclid=Cj0KCQjw_ZrXBRDXARIsAA8KauTNTLXRSqyi21BWPeKMwnsviU-by-WSTfDng7COVwCtnPWUIFPCQ-saAg9-EALw_wcB

other suppliers are available - I've never used these ones they just happened to come first on my Google search.

Remember they are also structural panels - ie self supporting up to their quoted span.

Edit, this is the supplier my son used for his house roof - replaced umpteen layers of felt on a shallow pitched roof:

http://www.griffithsandson.co.uk/acatalog/copy_of_Tractors.html

 

[bricol]

Used 6m long insulated panels for my garagea few years ago. Got Kingpsan seconds - top and bottom of the pallet/stack/ were damaged, but the centre ones were fine, so those and a cut-down damaged one sorted me.

My garage is a concrete pre-fab one. Put new 200mm purlins across, secured to angle iron brackets that allowed me to lift the roof to the maximum allowed before planning permission needed. Roofing panels on top, sheeted in sides, skinned with the old single skin steel roof panels cut to suit.

The white inside of the roof panels reflects the light rather well.

My only problem was the garage was 6.2m long - I should have put the panels on 20cm lower and added to the top end, not the bottom - just spent two days re-doing the lower end to cure a couple of leaks.

I ended up with 120mm thick panels as that's what they had - I would have gone for 40. IF you go the same route, don't forget the securing screws - sheet supplier will have the right ones.