Decra tile problems

[Steve Moisy]

Just wondering if anyone has had problems with leaks after fitting a Decra
tile roof?? I've just completed a mono pitch roof at 15 degrees with decra
plain tiles. I installed the roof following decra's instructions to the
letter but the first time it rained I had damp patches showing through my
breathable underfelt. I thought perhaps it was a problem with the nailing
so I've sealed all the nail heads - no improvement. I've sealed a few of
the side laps (although they looked fine) and it has made some improvement.
Decra's technical guy is going to have a look for me but I'm doubtful he'll
find anything wrong. £1100 on a roof and it leaks - I'm gutted. Anyone had
any similar experiences? Cheers - Steve

[David Hicks]

When you say breathable membrane, what have you used. Is it the right way up ?

What is beneath the tiles, insulation ? does the damp spots only occour during rain, are they in areas close to flashings, what purlins/ battens have you used, what fixings have you used.

There are so many things that can go wrong, see what your Decra rep says and if that does not fix your problems take some photos and come back

David



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[Steve Moisy]

Hi David thanks for the response. Can't remember the brand name of the
underfelt - on the bill it was listed as UV10 however, I can assure you it
is the right way up. There is no insulation as the roof is over a newly
constructed garage so I have a clear view of the underside of the felt. The
roof was installed to Decra specification using their supplied nails.
Rafters are at 500mm centres with 50X25mm battens. The damp patches appear
after about 30 mins of rain and seem to be below the areas where side laps
occur in the tiling. The damp shows through at points where the battens are
nailed to the rafters. The roof is around 8X3.2m - 70 tiles and there are
around 15 - 20 damp patches.

The Decra guy visited this afternoon and is coming back for a longer look
and to take some photos tomorrow. He commented that the roof was fitted to
a high standard and he was surprised at the problem. He was a little
concerned that the roof may be below the required 15 degrees. His angle
finder registered 14.5 one way round but 15.5 degrees the other way round.
I know it is 15 degrees exactly as I used a chop saw to cut each of the
rafters and my facia boards hang vertical off the ends. I've also rechecked
the underside of the rafters with an engineers protractor.

So for now I'll sit back and see where we go from here. I noticed on
Decra's web site that their products are guaranteed weatherproof if fitted
correctly - lets hope mine were. I'll post an update as and when.

Cheers - Steve
"David Hicks" <***@roofconsultant.fsnet.co.uk> wrote in message news:ci6n62$573$***@newsg1.svr.pol.co.uk...
When you say breathable membrane, what have you used. Is it the right way
up ?

What is beneath the tiles, insulation ? does the damp spots only occour
during rain, are they in areas close to flashings, what purlins/ battens
have you used, what fixings have you used.

There are so many things that can go wrong, see what your Decra rep says and
if that does not fix your problems take some photos and come back

David



********************************************************************************
DAVID HICKS ASSOCIATES LIMITED
Industrial Roofing & Cladding Consultants
Tel [phone] Fax [phone] Mobile [phone]
Visit our web site http://www.roofconsultant.fsnet.co.uk

Please note whilst ever effort is taken to ensure that emails issued from
this company are virus free, it is the recipient's responsibility to check
them before opening.
This company will not accept any responsibility for any loss or damage of
data howsoever caused

********************************************************************************

[David Hicks]

Interesting!

Please keep me informed.

David

[Steve Moisy]

Hi David
well the second visit wasn't very productive. The Decra technical guy took
a couple of photos and told me that in his and the technical departments
opinion my leaks are not leaks but condensation. I pointed out that I had
actually cut down the amount of leaks by sealing some of the side laps but
it fell on deaf ears. He also said that some of the tiles looked like they
were below the required pitch. I pointed out that the roof had the same
pitch all over and that if there were any differences it was due to
tolerances within the Decra tiles. I even showed him a tile that was 5mm
bigger at the front edge than another. This alone would throw the pitch out
between the two tiles. So we agreed to differ. He has asked me to monitor
the situation and to contact the managing director directly to voice my
complaints. I will be doing that as soon as I find time. Meanwhile I'm
rigging up a camera that I can pass down the laps in the underfelt so that I
can video the condensation (LEAKS) next time it rains. I'll keep you
updated and thanks for the interest. Cheers - Steve

Post by David Hicks
Interesting!
Please keep me informed.
David

[David Hicks]

Hi Steve

Without knowing much about the project, i.e. no piccys or drawings it is
difficult to assist. However, I must admit my first concern was that of
condensation if this is an uninsulated roof.
Is the roof over a closed or open area ? Do you have any vents from your
house discharging under the roof ? Send some piccys , you have my private
email address

David

[Keith@Hampshire]

Post by Steve Moisy
Just wondering if anyone has had problems with leaks after fitting a Decra
tile roof?? I've just completed a mono pitch roof at 15 degrees with decra
plain tiles. I installed the roof following decra's instructions to the
letter but the first time it rained I had damp patches showing through my
breathable underfelt. I thought perhaps it was a problem with the nailing
so I've sealed all the nail heads - no improvement. I've sealed a few of
the side laps (although they looked fine) and it has made some

improvement.

Post by Steve Moisy
Decra's technical guy is going to have a look for me but I'm doubtful he'll
find anything wrong. £1100 on a roof and it leaks - I'm gutted.

Anyone had

Post by Steve Moisy
any similar experiences? Cheers - Steve

Steve,
although I can't recall fixing Decra tiles, this all seems
rather confusing.
Is the underfelt breathable ie Tyvek, Corovin or similar.
From your comments later in this thread, condensation looks unlikely.
Monopitch is the simplest form of roof structure, as a last resort why
doesn't the underfelt keep the rain out ?

I learned recently that Eternit are reviewing their minimum pitch specs
due to a few failed roofs. (17.5 dg)

--
Keith.
http://mysite.freeserve.com/hampshireroofing/index.html

[David Hicks]

Hi Keith,

How are you keeping ?

I had a similar doubt, that's why I asked if it was the right way up.
Normally in these situations would you not use a "solid" membrane as a
vapour barrier rather than a breather ? Must admit my experience is usually
with large industrial type constructions with insulation to comply with
ADL2.

I think condensation is a possibility, Steve informs me there are no windows
installed yet, and if "warm" air is being trapped above the breather , then
condensation is a cert. However, if the breather is of the right sort, this
should run above the membrane to the gutter / outside.

Nonetheless, Steve is going to email some piccys soon, perhaps we can assist
more then.

I would be interested to know more about Eternit revisions if you have
details please. may help an argument I have on at the mo

Regards

David

[Keith@Hampshire]

Post by David Hicks
Hi Keith,
How are you keeping ?

Pretty good M8. How's yer car doing ? Plenty of mileage ?

Post by David Hicks
I had a similar doubt, that's why I asked if it was the right way up.
Normally in these situations would you not use a "solid" membrane as a
vapour barrier rather than a breather ? Must admit my experience is usually
with large industrial type constructions with insulation to comply with
ADL2.
I think condensation is a possibility, Steve informs me there are no windows
installed yet, and if "warm" air is being trapped above the breather , then
condensation is a cert. However, if the breather is of the right sort, this
should run above the membrane to the gutter / outside.
Nonetheless, Steve is going to email some piccys soon, perhaps we can assist
more then.

Yes, hope I get to see them. Am intruiged.

Post by David Hicks
I would be interested to know more about Eternit revisions if you have
details please. may help an argument I have on at the mo

Source is my son, who is a building surveyor for the local authority.
AFAIK, Eternit are rewriting their technical paperwork and raising the
minimum roof pitch (guess to 22.5dg)
I've fixed trillions of their cement fibre slates at low pitches without
any problems. Just always used 100mm headlap.

--
Keith.

[David Hicks]

Hi Steve

Please send you piccys to Keith as well.

Decra is not a system I have come across alot, but have used on a number of projects with which I have been involved.

However, we are talking PLAIN TILE here are we not ?


I am somewhat puzzled by your comments that when laid you only have a small to zero slope. If your roof is at 15 degrees ( and it looks about right from the photos ) then you should have a 6 degree slope on the tile. There is no alternative solution here, so I believe something may be wrong with the construction

Some of these questions may seem silly, and I am not attempting to "treat you as a child" , but often it is the obvious mistakes that catch people out

So :-
Are the battens all the same size and the right way round ?

Are the battens at the correct centres ? ( 160mm I think it should be) ? No intermediate ones that have been left in ?

If you still have an off cut, Check your breather as I described earlier. It is possible that it has been printed wrongly.

What variation do you have at the nib ( down slope turn down )

Are all the nails driven into the batten, or have any missed ?


I am sure Keith may have some ideas too

David



Keith

You private email is bouncing back, can you send Steve or I your correct one so we can forward the piccys,

[Keith@Hampshire]

"David Hicks" <***@roofconsultant.fsnet.co.uk> wrote in message news:cilrvt$mq4$***@news6.svr.pol.co.uk...


However, we are talking PLAIN TILE here are we not ?

Isn't it a steel panel ?
http://www.decra.com/products/tile.html

Ugh ! All merkan sites.

Keith

You private email is bouncing back, can you send Steve or I your
correct one so we can forward the piccys,

On it's way.

--
Keith.

[David Hicks]

Yep we sure is talkin' steel, but there are a number of different types,
each with different requirements

David

[West Stand Bowler]

Post by David Hicks
Yep we sure is talkin' steel, but there are a number of different types,
each with different requirements

Got the photos Dave, thanks.
There doesn't seem to be any fixing instructions on their website, but
here's my assessment.
Leak 1 is from the position where batten is fixed to rafter.
Was the underfelt fixed with clout nails ?
Leaks 2 and 3 are under the wallplate (and monoridge above).

Steve mantains that sealing the sidelaps has improved the situation.
However my feeling is a problem with *headlaps*

What is the recommended guage ?
What headlap does that achieve ?
Was it windy when these leaks appeared ?

IMO guage is everything in this situation.
No way is this condensation.
This looks like an exposed location.
Shame, as it's a tidy job.

Hope this is of some help.

--
Keith.

[David Hicks]

Hi Keith ( trying to confuse me with different names eh ?)

I would agree that condensation is unlikely given the locations but I would
not rule it out 100% as it is a new and wet building. We do not know the
state of the floor here either ?

However, I am intrigued as to how water is penetrating if the breather is
ok. It would suggest that the breather is ripped or possibly the wrong way
up ( despite what is written on it) and I await with interest Steve's
response once he does a small test I asked him to do.

I must admit the end laps would appear to be the problem from the info we
have todate. i.e. Steve is telling us that there is little or no slope on
some of the tiles. Is this because the tiles are not nesting properly,
the battens are of mixed size perhaps ? It is difficult to tell from the
photos, but irrespective of any of this, the membrane should keep the
water out. No matter which path I take, I always come back to the breather.

I have no idea what the steel sheet gauge is, but quite honestly over 160mm
you could use virtually anything, I suspect they have manufactured in 0.5mm
which is more than good enough for this.

Intriguing !!

David

[Keith@Hampshire]

Post by David Hicks
Hi Keith ( trying to confuse me with different names eh ?)

Sorry. I post to different groups under other names, and forgot to
change it back.

<snip>

Post by David Hicks
I must admit the end laps would appear to be the problem from the info we
have todate. i.e. Steve is telling us that there is little or no slope on
some of the tiles. Is this because the tiles are not nesting

properly,

Post by David Hicks
the battens are of mixed size perhaps ?

A possibility, but a long shot.
Battens are manufactured as nominal size, and actual size. There is of
course some slight variation with nominal, and considerable difference
in cost.

It is difficult to tell from the

Post by David Hicks
photos, but irrespective of any of this, the membrane should keep the
water out. No matter which path I take, I always come back to the breather.

Bottom line Dave --- no underfelt is designed to keep out rain long
term, the covering material has that job.
It's been common practice to fix underfelts by hammering a 65mm batten
nail halfway into the rafter and bending the nail over.
Clout head nails are a much better proposition

Post by David Hicks
I have no idea what the steel sheet gauge is, but quite honestly over 160mm
you could use virtually anything, I suspect they have manufactured in 0.5mm
which is more than good enough for this.

Sorry, I was reffering to the guage (distance between battens) rather
than the thickness of the steel.

As their sites all seem to be US, measurements are in inches, and
weights are in lbs !!
Looks like the recommended guage is 14.5 inches.
http://www.decra.com/products/PDF/t-s-sp-install.pdf

You'll need Adobe acrobat to read this .pdf file.
This measurement *must* be checked on site.Anything over this figure
will detract from the headlap of the next sheet.

--
Keith.

[Steve Moisy]

Sorry Guys Outlook Express has been playing up and only just managed to read all of the posts. I normally use Outlook for e-mail so I hadn't realised all this correspondence has been going on!!

In answer to the battens question - they were fitted using 75mm round head nails - the battens are 25mm X 50mm and were good quality with very little variation in size. I chalked the first row of battens then fitted each row afterwards accurately at 160mm to the bottom of each batten. The tiles are held in place with Decra nails. They are 50mm long hot dipped galvanized then coated with a bitumen type paint. Not sure why they have to be so long. There are 5 fixing per tile all were fitted by hand. The down turn nib is an interesting one because I have noticed there can be a 5mm difference between tiles on the bottom right hand side of the tile. This is the position where the side lap occurs and could force the side lap to be a little high. I still haven't checked the breather membrane but I will.

For Keith - leaks 2 and 3 were under the eaves not under the mono pitch. On Friday we only had moderate rain here - no gusty wind - and at the end of the day the damp patches were pretty well right across the eaves. Don't get me wrong- there was no water penetration just damp staining through the structure of the breather felt where it was getting in through the batten fixings but as you say Keith the felt is not designed to keep on keeping the water out. I'm sure at some stage it would fail.

As all of the problems have been occurring mainly at the bottom of the roof I spent some time over the weekend looking more closely at the bottom row of tiles. There seems to be very little pitch on the top section of each tiles. The situation improves after the halfway section of tile i.e. after the first 160mm. I'm sure it must be a construction problem but I followed Decra's spec for the laying out of the roof to the letter. On the bottom row of tiles there is only a batten at the top of the tiles - there is no intermediate batten to support or hold down the centre section of tile. Support for the lower part of the tile is given by an arris rail (looks like a big feather edge fencing board) 25mm X 200mm that runs the length of the eaves. The lower edge of the tile is secured by nailing through the tile into the facia board below. I'll pull off the drawing from the Decra site and e-mail it you David - it should explain better what's going on. The only other news I have is that the MD of Decra is paying me a visit on Thursday morning to personally look at my problem roof.

Thanks for all of the interest guys lets hope the MD feels like helping me out here.
"David Hicks" <***@roofconsultant.fsnet.co.uk> wrote in message news:cilrvt$mq4$***@news6.svr.pol.co.uk...
Hi Steve

Please send you piccys to Keith as well.

Decra is not a system I have come across alot, but have used on a number of projects with which I have been involved.

However, we are talking PLAIN TILE here are we not ?


I am somewhat puzzled by your comments that when laid you only have a small to zero slope. If your roof is at 15 degrees ( and it looks about right from the photos ) then you should have a 6 degree slope on the tile. There is no alternative solution here, so I believe something may be wrong with the construction

Some of these questions may seem silly, and I am not attempting to "treat you as a child" , but often it is the obvious mistakes that catch people out

So :-
Are the battens all the same size and the right way round ?

Are the battens at the correct centres ? ( 160mm I think it should be) ? No intermediate ones that have been left in ?

If you still have an off cut, Check your breather as I described earlier. It is possible that it has been printed wrongly.

What variation do you have at the nib ( down slope turn down )

Are all the nails driven into the batten, or have any missed ?


I am sure Keith may have some ideas too

David



Keith

You private email is bouncing back, can you send Steve or I your correct one so we can forward the piccys,