Flat roof replacement ... DIY ?

ric1982

Hi,

I have got a kitchen extension in the house with flat roof. Recently it had leak which I have temp. fixed. However looking at it, it prob. needs replacing. So I have got few roofers to get some quotes in. Roof is about 20 sq. f

Some are as follows:
- Roofer 1: £1000-1200 Felt roof , if changes in boards required then extra. 10 year warrantly
- Roofer 2: £2300 Felt roof with boards, £3600 for Fiberglass including boards and insulation. 30 years warrantly
- Roofer 3: £4000 fiberglass including boards and insulation. 25 years warranty

I dont think I want to do Felt roof purely because its lifespan and if anything goes wrong you have call roofer as it requires torch (I am not keen of hanling fire on the roof). I have seen lots of reviews both online and word of mouth about firberglass and most of them are positive. There are some exceptions such as someone compalins that it makes sound in high temp. But I think if done properly it can be avoided. The main thing is that because its cold installation , any future issues, I can fix it with DIY.

I have been looking at how the fiberglass is done. Although its not as straight forward, I think its DIYable. Does anyone has any experience doing DIY fiberglass? I am not a roofer but just rookie DIYer but think "I can manage it" (will see ofcourse).

There are lots of GRP (fiberglass) provider who can provide all the things needed so I think I can ge material and rools. For e.g. https://www.cureit.com/ .

Any suggestions?

smudger1964

Why dont you use epdm rubber it has a long life and is a diy fit too
https://www.rubber4roofs.co.uk/shop/?&mh_keyword=epdm%20roofing&bnine=true&gclid=CjwKCAiA6vXwBRBKEiwAYE7iS1HiuBW4_16aVA0rTXMuBtXzDnYRYcfkRq6lgbVlvF3t9knUKj9QOhoCqokQAvD_BwE


It comes in one sheet its so easy to fit I have done it on a large shed and a small lean to at rear of house

ANDY597

Plus 1 for epdm but must be laid on a fresh osb deck.

Youtube videos excellent for a flat roof installation.

Process is basically fresh osb deck maybe 22mm, dry weather, warmer weather is best, let epdm relax, roll on epdm water based adhesive which is a bit like pva, roll out 1 piece epdm and get rid of bubbles with a soft brush. Then epdm contact adhesive to edges, everything over laps fascia, then nail on drip strips. I'm summarising of course.

And you can live with some smaller bubbles although unsightly generally don't affect performance.

What's important is flashing where it meets house, have a look at lead replacement flashigng like ubiflex. Get this right or you will be ever regretting it with leaks.

Also plus 1 for rubber4roofs and roofingsuperstore

Hope this helps

ric1982

Many thanks for the detail responses.

I had a thought about EPDM and I know its prob. easiler to install then other two options. However I think laying the GRP is managable for me. My main concern is about increase in height due to Wram roof insulation which as follows:
- Laying ply on top of joist
- Putting vapour barrier membrane on the top
- Putting Insulation board
- OBS 3 T & G boards

(These are obviously rough steps)

Now once you lay this the height of the roof goes slightly up. Does this mean you have to adjust the facia boards? I got some pipes on the wall which I will need to box it. Any pointers about this?

Building Regs:

There is also one more query about how I go about doing Building Regs L? I know I have to apply in council. But once the work starts how do I arrange before and after inspection. Obeviosly once I open the roof I want to get the job done as soon as I can. Do Building regs inspector have to come on the site before and after or for this I can take before Pictures for before and during the work and just send them? Do I send plans in advance to the BR in case I miss something?

Thanks

FreeBear

Fascia boards - You'll either need to fit a new strip above the originals or replace with taller boards. Guttering will also need to be raised to suit the new roof level.

Insulation - Try to make sure it drops down around the perimeter to meet up with the insulation in the cavity (assuming cavity is insulated). Getting a good thickness of insulation around the perimeter will prevent cold spots forming.

Building Control - You should make contact with them before starting work. They will then advise on when they need to visit along with costs. Do take plenty of photographs before, during, and after.

When fixing the first layer of boards, use screws. If the plasterboard ceiling has been fixed with nails, using screws will limit the amount of nails "popping".

ric1982

Thanks everyone for their responses.

One of the rooffer who suveyed few weeks ago came back with a quote for a pitched roof (build over existing flat roof). So he is advising to put pitched roof over flat roof. Its was for £3800.00 which sounds resonable. Got couple of questions.

- Do I need Planning Persmission / Building Regs. as we are changing structure from flat to pitched. The roofer said you dont need PP/BR. But its me who is responsible so I have to do my own work but I was suprised that he said that.

- Is it a good idea to just build pitched roof over flat roof! (without removing flat roof) What type of issues can arise in future (condensation! for e.g.)

Any idea?

FreeBear

ric1982 wrote: »

- Do I need Planning Persmission / Building Regs. as we are changing structure from flat to pitched. The roofer said you dont need PP/BR. But its me who is responsible so I have to do my own work but I was suprised that he said that.

You most certainly will need building regs approval if you are putting a pitched roof on. You couldn't claim it is a "like for like" repair.
As for planning, it depends. Best thing to do is have a chat with your local planning dept. They will be best placed to advise as it will depend on things like permitted development rights, and if it is visible from the road, along with local planning policy. Get it wrong, and it will be you carrying the can.