If a terraced house had a slate roof with no underfelt, would this be
something that most people would want fixed immediately i.e. taking
off all the slates, and installing underfelt and replacing all the
Or is having no underfelt on a roof not a major problem, and something
which can be lived with i.e. not usually considered an "urgent"
Well it's not been urgent all these years has it?!
Providing the roof is intact and straight consider a foam type under tile
job. That will insulate and hold everything in place BUT is a bitch if you
ever do need to remove a slate cos it effectively glues them all together.
Our new (to us, built 1880) house doesn't have felt, and others in the same
street have had problems after felting theirs due to lack of ventilation to
the roof members. one thing about not having felt is there's plenty of space
for air to get in and dry things out. If the house was built without one,
just keep an eye out for missing tiles in high winds. If it originally had
one though, I'd be inclined to get it re-felted pretty quickly.
Well you quote one reason yourself, when (not if) the roof needs
repairing it won't be a straight forward job and you won't be able to
reuse any of the slates.
The of course when (not if) water does penetrate the slates it can't
dry out quickly and thus increases the chances that the rafters and/or
laths are going to rot.
In the short term, yes. But when the roof finally fails it will be a
much bigger and longer job thus more expensive.
Dave. pam is missing e-mail
i've had spray foam on mine now for 10 years and it is fine.
no more slipped tiles, a very warm useable roof space
reduced heating costs
and no condensation that people that don't know scare people with.
Dave Liquorice wrote:
So in another few years be prepared for *total* replacement of the entire
roof structure - or if you sell, a survey giving a negative report.
Roof timbers *need* to be ventilated on all sides - if you look at a new
roof you'll see ventilators fitted. Older roofs will allow enough airflow
*Growing old is inevitable, growing up is optional
Dave Plowman email@example.com London SW 12
I'm not about to be persuaded that spraying roof timbers with
foam is a good idea, but the key reason roof spaces are
ventilated is because the insulation is at ceiling level, the
roof space is therefore very cold and condensation on the
timber is likely without adequate ventilation. If you move the
insulation to rafter level the air in the loft space is that
much warmer and the risk of condensation substantially reduced.
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
It is certainly not unusual to get roofs like this, especially in the
North. The consensus seems to be that the lack of weatherproofness is
offset by the excellent ventilation (which quickly dries out any water
or snow that does blow in)! The roof space will also be pretty dirty.
I would say that if the roof looks in good condition (i.e. no broken or
displaced slates, no rotten or broken timbers) then this is not a major
problem. If you do need it doing, it is not normally hugely expensive
(maybe a couple of thousand pounds?).
On 7 Jan 2004 23:52:24 -0800, firstname.lastname@example.org (SuzySue)
It's very common indeed in older properties and is not a problem in
itself. Having felt provides a second line of defence in case a
slips out of place. Not having it means that you need to be a bit
more vigilant with keeping an eye on the roof from the outside and the
inside, since a slipped slate may mean water starting to come in.
Even then, if it is only one slate, the overlapping of the slates
would mean that that is not usually a major issue for a few days until
it can be fixed.
If the roof is in generally good condition, then it is reasonable to
leave it alone. On the other hand if the slates appear crumbly at the
edges or if you experience a lot of them slipping because the nails
have rusted, then it can make sense to have the roof relaid. This
involves taking the lot off, and the battens and then laying felt,
battens, probably re-using some slates and replacing others with
second hand good slates.
I would see what happens over the course of a year or so and then
decide. Obviously if there are any signs of water coming in or
slipped slates, these should be fixed.
To email, substitute .nospam with .gl
No. It's something you would address if you needed to refit the slates
for some other reason though.
Houses designed and built that way have survived hundreds of years,
so of itself, it can't be considered "urgent". Repairing a leaking
roof would be urgent though, e.g. if an unlined roof has misaligned
or missing slates.
If the slates are in good condition and well fixed then it's not a
problem at all. Once a slate slips though it needs to be attended to
with rather more urgency than on a roof with sarking.
Without sarking the roof space will probably be dirtier as windblown
atmospheric fallout (dust) will find it's way in. Stored items will
need dust sheets over them.
Dave. pam is missing e-mail
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