Hi,

My flat roof (over carport) needs replacing. I know I need to use 18mm
plywood and in another thread someone recommended to use aluminium
primer to seal the edges. Would you also paint top and bottom with
this; is it better than bitumen paint, and if so, why?

If you were applying felt with a bituminous adhesive, is it necessary
to paint the wood with bitumen paint first or would this be
duplication? IE is the bitumen in the adhesive sufficient to
waterproof the wood?

I see that toolstation also sell a bitumen primer, so how many layers
of bitumen are you supposed to use: primer, paint, and adhesive?

Regarding felt, I know not to use cheap shed felt, but I see that the
sheds sell top coat and undercoats. Am I supposed to lay two layers:
one undercoat with an overcoat on top? Does anywhere else sell them
cheaper than the sheds?

Is it worth painting over the felt with another layer of bitumen
paint?

Is there a slight slope on a flat roof? The current one seems to have
small wedges above the joists to lift the one edge, not that they seem
to have worked!

Finally, I was wondering about replacing the flat roof with a
polycarbonate sheet or something similar. However, the flat roof is
useful to stand on to repair the guttering, paint the fascias, etc. I
wondered whether to line the joists with wood and then fit the plastic
on top of this, so that if we ever needed access we could stand on the
wood. In this case, would you just paint the wood; after all it would
seem an unnecessary expense to felt it?

Thanks,
Fred.

Fred wrote:
Hi,

My flat roof (over carport) needs replacing. I know I need to use 18mm
plywood and in another thread someone recommended to use aluminium
primer to seal the edges. Would you also paint top and bottom with
this; is it better than bitumen paint, and if so, why?

If you were applying felt with a bituminous adhesive, is it necessary
to paint the wood with bitumen paint first or would this be
duplication? IE is the bitumen in the adhesive sufficient to
waterproof the wood?

I see that toolstation also sell a bitumen primer, so how many layers
of bitumen are you supposed to use: primer, paint, and adhesive?

Regarding felt, I know not to use cheap shed felt, but I see that the
sheds sell top coat and undercoats. Am I supposed to lay two layers:
one undercoat with an overcoat on top? Does anywhere else sell them
cheaper than the sheds?

Is it worth painting over the felt with another layer of bitumen
paint?

Is there a slight slope on a flat roof? The current one seems to have
small wedges above the joists to lift the one edge, not that they seem
to have worked!

Finally, I was wondering about replacing the flat roof with a
polycarbonate sheet or something similar. However, the flat roof is
useful to stand on to repair the guttering, paint the fascias, etc. I
wondered whether to line the joists with wood and then fit the plastic
on top of this, so that if we ever needed access we could stand on the
wood. In this case, would you just paint the wood; after all it would
seem an unnecessary expense to felt it?

Thanks,
Fred.

Try this link for some information on flat roofing methods:

http://www.ruberoid.co.uk/pages/rube...98FD0106209FOr if problems with the 'wrap' try this Tinyurl link:http://preview.tinyurl.com/5fa4tfScroll down to --- Waterproofers Handbook - Flat Roofing --- and downloadthe PDF data sheet - open the PDF and go to page 74 "Step-by-step fixingguide to Coldseal" and this may be of some help to you.Tanner-'op