I have a flat roof which is felted with a green mineral finish. It is now 24 years old and although it is not leaking I want to replace the felt before it does. I have some experience of burning on felt and I want to do a DIY job. My main question is; is it essential to remove existing felt or can I get away with laying new felt on top of existing?
Advice on renewing flat roof
- Thread starter beejaygee
- Start date
Sponsored Links
It is always best to completely strip the whole lot off.
You may want to upgrade to a warm deck (if there is not one there already) whilst you're at it.
Sponsored Links
Hi
Have you considered 'liquid plastics' or 'tor-coat' systems which can be applied directly over the existing felt. I don't know if you can get a DIY kit but it should be possible. Jet wash existing and allow to dry, roller on a base coat, apply a fibre embedment layer and finish off with either one or two coats of 'top coating' - all layers applied with a roller.
As already mentioned, you should consider adding insulation and apply the roofing system over the top of the insulation (suggest external PIR stuck to existing felt with occassional mechanical-screw fixings into underlying roof deck.) Insulation thickness - the more the merrier but if you want to conform to Building Regs you will need a minimum of around 80mm. Heat loss reduction will be from somewhere like 1.5W/m2K to 0.21W/m2K (apologies but I do not have time to carry out the detailed calculations although there may be someone on this forum who can point you in the direction of a freeby online calculator?)
Regards
Have you considered 'liquid plastics' or 'tor-coat' systems which can be applied directly over the existing felt. I don't know if you can get a DIY kit but it should be possible. Jet wash existing and allow to dry, roller on a base coat, apply a fibre embedment layer and finish off with either one or two coats of 'top coating' - all layers applied with a roller.
As already mentioned, you should consider adding insulation and apply the roofing system over the top of the insulation (suggest external PIR stuck to existing felt with occassional mechanical-screw fixings into underlying roof deck.) Insulation thickness - the more the merrier but if you want to conform to Building Regs you will need a minimum of around 80mm. Heat loss reduction will be from somewhere like 1.5W/m2K to 0.21W/m2K (apologies but I do not have time to carry out the detailed calculations although there may be someone on this forum who can point you in the direction of a freeby online calculator?)
Regards
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
