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Andrew Mawson Andrew Mawson is offline
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Default what is the fabric for under the roof tiles?


"RobertL" wrote in message
ups.com...

My house was built in the 1960s and like many it has heavy roof

tiles
that are laid on battons which are fixed to the rafters. The tiles
seem to be held there by gravity alone - each one has a lip that
engages with the batton. Between the battons and the rafters is a
sheet of bituminous cloth (it looks like).

What is the purpose of this cloth?

Is it to stop the wind which might otherwise (1) blow water up the
tiles and into the roof space and (2) lift off the roof tiles? or

it
is to catch any water that does leak in and guide it to the gutter.

I want to cut this cloth in order to remove as small patch of tiles

so
I can do some ridge repairs without having to climb onto the outside
of the roof.

When I repair it afterwards does it need to be watertight or simply
windproof?

Thanks,

Robert


It's called Sarking felt, and is there to stop rain and snow being
blown into the loft by an unfavourable wind. It also stops a load of
crud being blown in keeping the loft cleaner. Conventionally it is
laid from the roll parallel to the guttering, starting at the bottom
of the roof. Each subsequent strip being laid to over lap the previous
one by 4"-6". At the ridge, a roll is laid so that half goes down one
facet of the roof and the other half down the other facet. This gives
a waterproof seal so anything blowing under the tiles will run down
the outside of the sarking felt and down into the gutters, as the felt
should overlap the gutter board slightly and dip into the guttering.

You will find that the bituminous type will be very brittle by now and
will probably crumble as you try to remove it. Modern sarking felt is
a plastic sheeting, grey on one side and black on the other, with a
square nylon reinforcing mesh embedded between the layers.

Although you ought to be able to remove the tiles and felt, and do
your ridge repairs 'from inside' I cannot see how you can correctly
replace the sarking and tiles in a weatherproof fashion from inside.

If the tiles were laid correctly every third row should have been
nailed to the battens - or even every row if in an exposed position.

AWEM