Felt Roofing?

Hi,

I have a flat garage roof that has started to leak. It currently has chipboard beneath the felt, which has started to expand and rot. So I need to totally replace the roof, replacing chipboard with 18mm WBP ply, then 3 layers of felt (2 underlay 1 top) Now my question is, the 1st layer of underlay, should I nail it to the ply boards, stick it, or leave it free moving. I read this website

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that says to nail the felt every 6" (using proper felt roofing nails), however I was talking to our 2 builders/maintenance contractors at work and they said if you nail it, when the felt expands, it rips, so you should just lay it on, and not nail/stick it.

Who is right?

Any help greatly appreciated!

Cheers

Ben

"Thanks to God, I am Still an Atheist"

Reply to
Ben
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You are better to nail the first layer to the boards, but not as close together with nails as the site says, as far as I've been told anyway. The roofers who did ours a couple of years ago went with a spacing of nearer the

9 inch mark with nails as far as I could see when I was eaves dropping (I always try to pick up tips when we have tradesmen in), and they did use proper roofing felt nails as well. They then stuck the second layer on top of this with liquid felt adhesive, which they poured out of big tins and spread it out with clean mops, all over the bits they were about to roll the next layer of felt down on. The also nailed the joints of the second layer with roofing nails and, as before, they also used a spacing of around the 9 inch mark again.

The top coat was then laid with hot bitumen slugs, which they melted in a big vat that they'd lifted on to the roof beside them. This was spread around the area as the top coat was being rolled out on to the hot tar. The same hot bitumen was also used to seal all the seams before the green mineral chippings were sprinkled over bitumen to make the felt al uniform again.

Reply to
BigWallop

Thanks for the reply BigWallop. We had our porch done a few months back, and I wish I'd been able to watch, so I could pick up some tips to use this time around, but I was at work.

I went to Wickes tonight to price up some materials, and I see they do an 'easy seal self adhesive' felt system. Anyone have any experience with this system? It maybe easy to lay, but does it stand up to the weather?

Also they do 2 types of underlay & top cover, either a 5 year or a 10 year guarantee. Trouble is, the 10 year is 3x the price of the 5 year. If I were to lay the 5 year underlay, and then the 10 year top cover over it, would the underlay still be OK after 10 years, or would it perish?

Ben

Reply to
Ben

Never, ever, nail felt! This makes holes in it, unsurprisingly. It should be stuck using the appropriate adhesive which should be laid in stripes up and down the roof at, say 1 foot intervals. If you plaster the whole roof with adhesive it is likely that when the felt gets holes in it the rain water will gather, unable to get out by gravity, whereas with 'vertical' glue the water, if any penetrates the felt, will run out to the gutter. The you glue a top sheet on top.

Rob Graham

Reply to
Robin Graham

I've used cheapo felt and good felt, and I'd always use the best if the money's there. Its a small difference to pay to make the roof last twice as long.

I've never tried fibreglass resin roofing, but have heard its much better, might be worth looking into.

NT

Reply to
bigcat

The message from snipped-for-privacy@meeow.co.uk contains these words:

Is this something you can buy off the shelf and stick on or do you have to do a wet lay-up on the roof? I would have thought doing a wet lay-up on a sloping roof would be awkward to say the least.

Reply to
Roger

Its rigid, so its a wet lay job.

NT

Reply to
bigcat

God may be an Atheist for all I know Ben, But I believe in this product, If its still made that is.

There is a product that is Torch-On it is heated with a blow torch and rolled on to the roof also there is a product called Colas which is a modified bitumen co-polymer (sorry if spelling wrong) which does not harden when exposed to ultraviolet radiation the polymers are arranged in long strings so the bitumen stays pliant (soft) and is guaranteed for 25 years a good roofer will use this type of bitumus felt, a cowboy some thing from a DIY store.

MikeS

Reply to
MikeS

hello ben, well i'll start by saying that you need to forget about the felt thats sort of like the vcr compared to dvd have a new grp roof it lasts forever its not effected by the change in weather and with the felt you can almost rest assure you'll be paying out again. many people are having garage roofs,flat roofs asbestos roofs replaced with grp roofs. if you need more advice on where to look for this service contact me snipped-for-privacy@hotmail.com

Reply to
kev

grp has two layers the top layer being a coloured gel coat 100% water/weather proof.

Reply to
kev

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