Following on from my other thread about lock-ups… I’ve been round to check a few things and discovered the roof is leaking badly. There are a couple of small cracks but it looks like most of the roof material has become porous. It is pretty old though.

It looks like it’s made from the concrete/asbestos fibre material. A rough measure and it’s approx 150mm between peaks and the peaks are approx 50mm tall. I think it may be B6?

I’ve seen a couple of products which you paint on – Acrypol or Flexacryl

These are not the cheapest but I would hope that at the price they would work? I don’t mind paying for one of these products if they do work.

Or is there sheeting available which I can simply lay directly over the top of the existing roof and thus not disturb the existing roof?

Or should I just remove the lot and replace?

It’s not the best time of year for removing and replacing I know…

If one of the above paint on products worked I may use it and replace the lot in summer…

Thanks again

It’s not the best time of year for removing and replacing I know…

Encourages you to do it in a hurry though, I had a workshop in a place i used to live in up north that I built from ground up in 3 short december days just to get out of the fricking scottish wind and sleet.

I’ve seen a couple of products which you paint on – Acrypol or Flexacryl

maybe less the time of year for using something like that. Decades ago I helped my day fix a leaking flat roof with something similar (a kind of black/brown acrylic porridge) Cold weather meant it didn’t dry/set properly, then frost followed by rain meant it thawed and leaked sticky gunk into the house. Yay.

flexacryl probably won’t work on asbestos to well too be honest, if the material is porous its probably soaked up a lot of water, the flexacryl will just stick to the top layer and when it dries will probably flake off. i’ve done loads of repairs like this, only in the summer tho, and then had to use a blow torch to dry it, then used flash band. if you can, i’d re roof, should only take a few hours if its normal garage sized

A couple of things i would consider in your situation. Is the roof fragile ei are you likely to fall through it trying to waterproof it.If you are using it as a commercial property you will come under management of asbestos in the workplace legislation. If it is old and friable as you describe it, will people within the unit be breathing in asbestos dust. If you have long term plans for the property it would be prudent to remove the roof and replace with felt or single ply membrane. Hope this helps

plenty of things you can do, if you want to go the overlay route, which is fairly common for industrial building. screw some spacer bars on top and fix steel sheets to the spacers, it is often an excuse to uprate the insulation as you have a void you can fill with rock wool/glass.

http://www.ashandlacy.com/ashgrid/
http://www.qbmdistributors.co.uk/case-studies/180
http://www.makfasteners.com/Products/ByProduct/SupportBarSystems/Gridtite.aspx
http://www.metsec.com/products/cold-rolled-steel-purlins/steel-purlins-Z-sections.asp

or just get purlins and run them across the top, if your not bothered about going the purpose built route, timber batons fixed to the existing roof and then another sheet on top would do it. Only thing to be aware of going that route is that any moisture in the cavity can cause the timber to rot and take the steel with it.

If its basic chrysotile then I’d strip it and reroof. If its as brittle as you say getting access up there to “paint it” is going to be a ball ache! Modern cement based sheets are still widely available and are used on most prefab cow sheds/barns etc.

Mrmo’s idea is great btw and will give you the most secure and “best job”, I’ve been involved in similar many a time but its more costly, plus you’ll need all the associated flashings etc.

I have a big old cow shed with this roofing. It started leaking a bit (cracks in the corrugated valleys) and I just smeared some silicon over the top from the outside.
That was about two years ago and it’s still dry. I would love to replace the entire roof though but it’s 60′ x 40′ so would be £££

I had this problem a few years ago (exactly as you describe).

Just ripped the whole lot off and replaced it with a tin roof.

Back then, the council tip was happy to receive trailer loads of asbestos cement material (just went in a ‘special’ skip marked ‘asbestos’). Most councils are a bit more restrictive about the amounts they will take nowadays, but more out of concern not to take ‘trade’ waste rather than on H & S grounds.

You also need to be licensed now.

Thanks everyone!

It’s not so brittle that I can’t get up there – I use a makeshift crawler board and it’s fine.

I’m interested into the silicon product you used sharkbait? This may be a good temporary solution until summer.

I’m thinking batons and a new roof over the top may be the best solution. This lock-up is in the middle of two others so ripping out the current roof could be a right pain. Something over it would be far more simple…

I just used some standard marine sealant because that’s what I had.
As Silicon sticks like sh*t to a blanket I think any waterproof type would do – preferably clear.

To try and identify the sheet profile can be tricky:
http://www.slecladding.co.uk/asbprofiles.htm

http://www.marleyeternit.co.uk/Profiled-Sheeting/Profiled-Sheeting-products/Profile-6.aspx

Some councils are more helpful than other at getting rid of asbestos cement:
http://www.birmingham.gov.uk/asbestos

http://www.cheltenham.gov.uk/info/200075/pollution/602/asbestos-facts_removal_and_disposal/2

http://www.medway.gov.uk/environmentandplanning/wastemanagement/asbestosdisposal.aspx

You can get tins of roof sealant that can even be brushed on when the roof is wet. But they tend to be so expensive that it can be better to re-roof (with new roof-sheets) than to try to repair old roof-sheets.

Renewing sheets even in the middle of a roof (eg if you have neighbours either side) is not easy if the roof is wet and slippery and fragile. But if you can get on the roof and remove the fixing nails / screws then the old sheets can be slid out, and new sheets slid back in.
The old sheets will be very heavy and difficult to handle and will probably break up. New sheets tend to be a lot lighter and flexibile.
The difficult bit is getting back onto the roof to fasten the new sheets down, drilling screw-holes etc.

Some scaffold does make a difficult (dangerous) job a bit easier.

But the other problem is that if you remove some old sheets: you may find that you damage some of your neighbours sheets and your new sheets (even if you have the right size and shape,profile) will be a little bit thinner and might not match in with the old quite as easily as they could (slight gaps in the height of new sheet to old sheet).

http://www.hse.gov.uk/asbestos/licensing/notifiable-non-licensed-work.htm

“NNLW will not normally include the following, which will continue to be categorised as non-licensed work (which is not notifiable), (assuming in all cases exposure is sporadic and of low intensity and will not exceed the control limit):

short, non-continuous maintenance work involving AIB which is in good condition, e.g. drilling holes in AIB to attach a fitting or pass through a cable or pipe, cleaning light fittings attached to AIB, removing a door with AIB fire-proofing, or lifting ceiling tiles for inspection where there is no full-body entry into the roof space;
short, non-continuous maintenance work on asbestos cement (AC), e.g. work on weathered AC roof tiles;
removal of AC, which is kept virtually intact;
“
AC = asbestos cement