Weatherproofing and sealing a building roof?.

  spuds 12:29 07 May 2013

I recently raised a question about Warping on timber fencing structure, and some very good results came from that, so here's another topic possibly for discussion?.

Have ever used or possibly know anything about Fibreglass type or GRP roofing resin, and if you have, would you care to share any experiences on that product or something similar for roofing and weatherproofing?.

  spuds 10:55 08 May 2013

Perhaps I should add further, we have had a 'specialist' GRP roofing company in already, and they made the suggestion that 'all' the outbuilding roof's would benefit by their provided services. Apparently they give three coats for added future protection, this is based on any pre-remedial work required.

Their work comes with a manufacturer's 25 year warranty, but like oresome may have suggested, we are a little concerned about this guarantee?.

The individual outbuildings consist of either flat roof with OSB and two layers of heat sealed felt, with top layer of heat sealed mineralised felt. The other outbuildings consist of pitched roofs with either corrugated steel, corrugated bitumen sheets or 'asbestos' type corrugated sheets.

The OSB/Felted flat roof and one of the corrugated bitumen sheet roof's had a recent incident, when early one morning we had intruder's who 'went through' part of the roof's, hence the question on using GRP?.

  Woolwell 11:15 08 May 2013

carver - you have provided 2 links to the same company.

spuds - I have come across GRP and felt on flat roofs. In my experience GRP, provided it is installed properly and has insulation, is fine but possibly can be more difficult to repair. It will last as long, if not longer than felt. However felt has improved a lot in recent years and if looked after will last just as long. The early GRP roofs could be prone to degradation from UV especially if not installed properly but that shouldn't be a problem now. The problem is avoiding the cowboys who promise that a product will last forever and be no maintenance.

  spuds 11:38 08 May 2013

Woolwell - that's one of the problems 'cowboys', but the company we contacted seemed to have the 'correct credentials', even though they appeared to be perhaps covering themselves with the manufacturer's 25 year guarantee.

We can buy the 20/25 litre drums wholesale, but its just a case of perhaps having the knowledge of doing the 'weatherproofing' to industrial standards. We already have the equipment for possibly doing the work?.

Not sure about the length of time the felt flat roof was originally installed, possibly 'upto' ten years or so, so its had a good innings with minor maintenance. the only way we found out about OSB being rotten in certain areas, was due to the recent intruder incident. Luckily the person or person's involved managed to save themself before completely falling through the roof's, otherwise with the drop and heavy machinery being present below, things could have been really serious for someone?.

  carver 11:39 08 May 2013

spuds what is the time limit on your use of the buildings, it is no good spending a small fortune having GRP products to all the building if you only intend to use them for 10 years.

Don't forget they are there to sell you their product.

Have they explained that the top product is only as good as the base onto which it is applied.

That 25 years warranty is only as good as the small print, a good felted roof will give you 20 years at 1/2 the price, a bad GRP roof can give you 10 years.

"'asbestos' type corrugated sheets" can be made good, and with all the fuss about asbestos and associated problems are best left in place and treated with some thing like this enter link description here it's only one of hundreds of products for doing the job.

Any roofing supply company worth it's salt will point you in the right direction as to which product is best for you.

Corrugated sheets are best replaced with same, other wise you will have added cost of having to fit extra purlins to carry a base for top coat, whether it be felt or GRP product.

You can contact a wide range of industrial roofing supply company's who will have a range of surplus sheets only too willing to sell to you at a small % of cost.

If a felted roof has gone then be prepared to replace boards to carry the felt, you are best to replace any rotten boards with a good quality exterior ply, this will give you a very good base layer.

A bit of reading here enter link description here

  spuds 11:48 08 May 2013

carver - thanks for that, I'll look further into the links provided later today. I have a medical appointment to attend shortly, which may take up a couple of hours or so.

  carver 11:57 08 May 2013

Woolwell so sorry, must try better.

  Forum Editor 15:00 08 May 2013


Settle down - there's no call for unpleasant sarcasm - nobody's questioning your experience in the roofing trade. As you often do, you've been so keen to take offence you've overreacted to something you thought I said, rather than reading what I actually said.

Note the words "conventional pitched roof." in my post, and then think about it. Tell me how many houses with conventional pitched roofs you've seen with GRP coverings. The answer should be 'none'. The reasons are:-

a) because a normal house roof pitch is too steep for the material to be easily laid - GRP has to be laid onto a decking base, and with your years of experience in the roofing trade you would know how difficult it would be to walk up and down a ply-covered 42.5 degree roof pitch with a tub of acetone and a roller, laying chopped strand matting into an acetone film. You simply wouldn't be able to do it easily or economically carver, and it's the reason why neither of the companies in your links show photographs of a semi-detached or detached house with a GRP roof cover.

b) because there would be planning issues. The appearance of a GRP roof covering isn't acceptable on a row of 1930s houses that were designed and built to have tiled roof coverings.

All roofs are pitched to a degree, including those called 'flat' roofs, and that's precisely why I included the word 'conventional'.

  oresome 16:58 08 May 2013

In the property I mentioned in a earlier thread, one area that was eventually found to leak was where the corrugated sheeting overhung the gutter.

In extreme conditions, the gutter overflowed and water went under the sheeting and into the building. The secondary membrane did nothing to prevent this as it stopped at the roof edge and in fact probably shouldn't have been applied in the first place had a correct diagnosis of the original problem been made.

  carver 18:33 08 May 2013

F.E I asked a very simple question and you jumped down my throat, no question about why I had posted such a question just,

"it's obviously a flat roof - see my response. You don't have purlins in a flat roof construction,and you wouldn't use a resin-based covering on a conventional pitched roof."

just what do you class as a conventional roof and what pitch would you say it was, because I can assure you that a "conventional" roof with the correct tiles can go down to a pitch as small as 25 degrees, a sheeted roof can go down to 15 degrees and on 1 occasion I have actually done one with a 12 degree slope.

And then you say don't be sarcastic, at least I'm not rude to start with.

But then you are the F.E

  Forum Editor 23:13 08 May 2013


I'm not going to get into an argument about roof pitches - the minimum of 15 degrees is a building regulations requirement for a tiled roof, but a pitch that low is uncommon in domestic dwellings, except on the occasional lean-to extension. it's a fact that in the UK the typical pitch angle for a house roof is between 30 and 45 degrees - far too steep for a GRP covering to be a practical proposition, quite apart from the planning issue.

I didn't jump down your throat carver, and I note that you still can't stop yourself from making nasty little remarks about me.

This thread is now locked and can not be replied to.

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