Understanding Roofers' quotations

[Paul.A.Bowden]

Apologies if this posting is inappropriate, but I would really appreciate any advice, as this job is well beyond a limited DIY-er like me. I have had two quotations to repair a flat garage roof, which has just started to leak. They are wildly different in price and, while there may well be other factors, I wonder whether the difference lies in the specifications which I will quote below. Both propose stripping away existing felt etc and then EITHER (quoted exactly in each case) FIRST FIRM

1. Lay three separate layer soft 747 BS ruberoid flat roofing felt, each sealed with hot bitumen so to bond together
2. Finish all edgings with 36 KG green mineral felt
3. Cover whole of the roof area with solar reflecting alloy paint

SECOND FIRM

1. Fixing new built up felt roof covering comprising base layer of type 3B felt fixed to existing decking and a cap layer of MP400 torch-on high performance mineral surfaced felt including for MP400 mineral surfaced felt to all perimeter details.

We're on a VERY tight budget and won't necessarily be in the property for ever (but certainly for the next 5 years or so and, anyway, we'd like to be able to sell it in a good condition), so want to pay as little as possible, consistent with getting a reliable job done. We would be so very grateful for any advice. (PS: I haven't indicated which of the quotes is higher/lower and wonder whether the specs make it obvious?) Thanks so much in advance for any advice or comments Paul

[Dave Baker]

What type of material is the roof covered in at present? Felt with stone chippings covering it maybe?

If the leak is just in one place then if you can find the problem you'll get a decent repair just by brushing any chippings to one side, slapping a coat of roofing mastic on it and putting the chippings back. It's quite possible the rest of the roof is in good condition and will last as long as you need it to.

[John Rumm]

That one will give you the better job...

Torch on is good, but not as good as a hot bonded solution IME.

[Martyn Pollard]

What about using a fibreglass system? Some firms do specialise in this method and I doubt it would cost you much more than a quality felt roof.

It has to be applied in a timely manner before the resin sets. You will know you have a watertight roof which can be repaired and painted in the future without having to tear it all off and start again.

I think there is one online firm which sells all the resins, top coat paints, trims etc.

Martyn

[Bob Minchin]

I had the first type of roofing (although without the reflective paint - I had granite chippings instead) on an extension and got 20 years out of it before a leak. I think it came with 10year guarantee. It has just been replaced with the second type of roof. It now has a 20 year guarantee and the fitters said it should lasts 30 years. The felt they used had fibreglass re-inforcing in it.

I suggest you ask about guarantees from both suppliers and go with the cheapest who offers sufficient guarantee to still have some left to pass on when you sell.

If your garage has a chipboard decking and it has been leaking, be aware that you might well have to have new decking. This could be a DIY job if you wanted to save money.

good luck

Bob

[Paul.A.Bowden]

Thanks to all of you who have taken the time to reply. I posted the same question in free.uk.diy.home and one person replied recommending FIRM 2 quite strongly. For the record, the two quotes are Firm 1: =A3675 and Firm 2: =A31420. Quite a difference! I'm INCLINED (not surprisingly, I suppose) to go for the cheaper option. The respondent in the other NG said that the solar reflecting paint needed redoing every 18months - 2 years, which I'm assuming is not too hard, even for someone pretty incompetent, like me. Any final thoughts, advice, comments etc would be very welcome. Meanwhile, thanks again Paul Lincolnshire

[John Rumm]

Both fibreglass and some of the rubber membrane roofing systems are supposed to give a longer lasting result that felt. Having said that the level of succcess with felt does seem to vary quite a bit depending ont he skill of application and the quality of the sub base.