Re-clading roof

[timhaven]

Hello,

Just bought some box profile cladding to re-clad roof.Tec screws surplied are only 45mm long,fine if fixing in the trough,but not through the ridges.Have always nailed/screwed through the ridge with corrugated/box profile sheets as thought doing it in the troughs would cause leaks.The roof has a very shallow pitch whitch makes me nervous,as the smallest of holes lets in water.These tec screws do have rubber washers.Do I send screws back and get longer ones?.

Any advice would be appreciated thanks.

[him]

send them back, ur thought on leaks is correct, it would rust like hell too aroud the washer.

[timhaven]

send them back, ur thought on leaks is correct, it would rust like hell too aroud the washer.

Thanks for that,that's what I thought.Might as well get it right

[Derky]

What you screwing into wood or z purlins ? If z purlin you want tec screws or wood you want drive screws.

[timhaven]

What you screwing into wood or z purlins ? If z purlin you want tec screws or wood you want drive screws.

Wood.Screws have correct thread for wood,but just aren't long enough.

[timhaven]

Just rang the surpliers of the cladding,they say drill through the troughs as screwing through the ridges will distort them

[Courier]

Just rang the surpliers of the cladding,they say drill through the troughs as screwing through the ridges will distort them

If you are fastening on to treated timber then put a layer of dampcoursing between the wood and the sheets and it will hold back the corrosion for a few years longer.

Quite normal on modern (1970's onward) box section sheeting and should last 20 odd years or spend more and get some proper 3" profile 0.7mm corrugated.

Is the shed going to be for dry storage or will it house livestock and will the ventilation be good enough to prevent lots of acid condensation.

[timhaven]

If you are fastening on to treated timber then put a layer of dampcoursing between the wood and the sheets and it will hold back the corrosion for a few years longer.

Quite normal on modern (1970's onward) box section sheeting and should last 20 odd years or spend more and get some proper 3" profile 0.7mm corrugated.

Is the shed going to be for dry storage or will it house livestock and will the ventilation be good enough to prevent lots of acid condensation.

Just recladding 2-3 bays of a lean-to for grain storage,so can't have any leaks at all.Timber beams at least 40 years old so don't know about any treatment(bit of wood worm though).
This shed was cobled together in the 60's from bits of WW2 aircraft hangers by previous owner.Should really Knock it down and start again

[Quattromike]

Make sure you have the correct profile for the roof witch has a narrow flat on the top of the ridge and the wide flat on the bottom. If it's the other way round you have wall sheets. Definitely screw through the top of the ridge.

[Steevo]

If you are fastening on to treated timber then put a layer of dampcoursing between the wood and the sheets and it will hold back the corrosion for a few years longer.

Quite normal on modern (1970's onward) box section sheeting and should last 20 odd years or spend more and get some proper 3" profile 0.7mm corrugated.

Is the shed going to be for dry storage or will it house livestock and will the ventilation be good enough to prevent lots of acid condensation.

Please could you expand on this.

Dampcoursing - just over the timber, under the tin? Small strips, or full sheets like roofing felt?

Are you suggesting that 3" corrugated (round profile rather than box?) will last longer than box? How so please?

[Hesston4860s]

Please could you expand on this.

Dampcoursing - just over the timber, under the tin? Small strips, or full sheets like roofing felt?

Are you suggesting that 3" corrugated (round profile rather than box?) will last longer than box? How so please?

We used the damp coursing same stuff as you would use on brick work, comes on a roll bout 4 inch wide.

[timhaven]

I'm going to drill through the ridges.As for 3" corrugated sheets,thats what's on there now.With the sort of rainfall we have had recently water seems to overwhelm the corrugations and seep through the sides.Sheets were riveted down the sides to try and stop this but has failed to work.Sheets seem paper thin aswell,I'm thinking they tried to economise by using side cladding on the roof?All in all a right bodge up,so that is why I chose box profile sheets.Corrosion seems to be where sheets overlap,rather than where they touch the timber purlins,so would a damproof sandwich where sheets overlap be sensible?

[sprocket]

If you put the screws through the ridges you will need some sort of packing under every screw. Otherwise as the manufacture says it will distort and the sealing washer cannot be watertight.

[Dry Rot]

Reading these posts (and especially the OP) scares me to death.

Loads of information on the Internet about fixing box profile. The suppliers are correct. Drilling through the ridges will distort and weaken the roof. They don't design this stuff the way they do to work if people will fix it the wrong way! I wonder if the insurance will pay out when it blows off?

Just Google "fixing box profile".

[timhaven]

Reading these posts (and especially the OP) scares me to death.

Loads of information on the Internet about fixing box profile. The suppliers are correct. Drilling through the ridges will distort and weaken the roof. They don't design this stuff the way they do to work if people will fix it the wrong way! I wonder if the insurance will pay out when it blows off?

Just Google "fixing box profile".

Pictures on internet are of steep pitch roofs.Mine is very shallow,40' length and only 1 foot drop.Just wanted plenty of advice that's all.
Insurers won't pay up if sheets blow off because can't afford to insure shed in the first place.It's also due to lack of funds that I'm pissing about doing the job myself.In an ideal world shed should be replaced altogether with a new one of better design.And don't bother telling me not to fall off.That bit I've worked out for myself.

[Dry Rot]

Pictures on internet are of steep pitch roofs.Mine is very shallow,40' length and only 1 foot drop.Just wanted plenty of advice that's all.
Insurers won't pay up if sheets blow off because can't afford to insure shed in the first place.It's also due to lack of funds that I'm pissing about doing the job myself.In an ideal world shed should be replaced altogether with a new one of better design.And don't bother telling me not to fall off.That bit I've worked out for myself.

OK, I understand. But I think the advice about drilling through the troughs still holds true, though perhaps a dab of silicon sealant as well as the supplied rubber sea; would not go amiss, especially at the overlaps.

I will try to remember not to reply to posts too early in the morning next time!

[timhaven]

OK, I understand. But I think the advice about drilling through the troughs still holds true, though perhaps a dab of silicon sealant as well as the supplied rubber sea; would not go amiss, especially at the overlaps.

I will try to remember not to reply to posts too early in the morning next time!

All the cladding manufacturers on the net say drill into troughs,but must be drilled in straight,and don't overtighten/undertighten.Get it wrong and there will be puddles.My 12 volt drill isn't powerfull enough to overtighten and distort ridges,but I take your point about wind.If wind gets under the ends they could lift and then distort sheets.I'm going to drill both ridges and troughs on the ends to make sure that doesn't happen.

[Courier]

Mine is very shallow,40' length and only 1 foot drop.

Ours erected in 1974 was 1 in 80

[timhaven]

Ours erected in 1974 was 1 in 80

Well,flat roofs were popular in the 70's
Any leaks?,if not I'm flabergasted.

[Olliedog]

Hi,
The fixing through the troughs is 100% accurate.
We have sheeted hundreds of sheds and they are always fixed through the troughs.
The idea is that fixing through the trough will give a firm fixing of the sheet to the purlin, a fixing through the peak will allow the sheet to flex and in time loosen the fixing.
The rubber washer on the fixing screw should have a steel washer above this and under the head of the screw. tighten the screw just so much as to slightly compress the rubber washer. Over tightening this will squash the rubber and may cause a split. the rubber washer will provide sufficient seal to stop leaks.
We have just re-sheeted a roof similar to yours that the farmer had had issues with fro the last 10 years. Overnight all leaks were eradicated.
As previous posts, make sure that you have been supplied the correct roof profile and that it is 0.7mm thick, cheaper wall profile (generally 0.5mm thick) will not do the job.
The fixings are a matter of 'you get what you pay for' we use a good quality plastic capped timber tec from Ash and Lacey
Cheaper screws have a tendency of allowing the plastic head to 'spin' around the internal steel head.
Always use the correct hex bit for your drill as a standard socket will not fit (it may seem to at first but it will not drive the screw in all the way).
Never used a damp proof course, but I can see possible benefits.
Hope that this helps!

[him]

Hi,
The fixing through the troughs is 100% accurate.
We have sheeted hundreds of sheds and they are always fixed through the troughs.
The idea is that fixing through the trough will give a firm fixing of the sheet to the purlin, a fixing through the peak will allow the sheet to flex and in time loosen the fixing.
The rubber washer on the fixing screw should have a steel washer above this and under the head of the screw. tighten the screw just so much as to slightly compress the rubber washer. Over tightening this will squash the rubber and may cause a split. the rubber washer will provide sufficient seal to stop leaks.
We have just re-sheeted a roof similar to yours that the farmer had had issues with fro the last 10 years. Overnight all leaks were eradicated.
As previous posts, make sure that you have been supplied the correct roof profile and that it is 0.7mm thick, cheaper wall profile (generally 0.5mm thick) will not do the job.
The fixings are a matter of 'you get what you pay for' we use a good quality plastic capped timber tec from Ash and Lacey
Cheaper screws have a tendency of allowing the plastic head to 'spin' around the internal steel head.
Always use the correct hex bit for your drill as a standard socket will not fit (it may seem to at first but it will not drive the screw in all the way).
Never used a damp proof course, but I can see possible benefits.
Hope that this helps!

never done it that way before, never will in future either for cattle shed anyway, machinery not likely either. can see where ur coming from with the argument on distortion, but as im sure u know its the man on the drill.

when u would have to nail on a roof where would u put the nail? black rubber washer type nail.

[wr.]

Tec screw ALWAYS in the trough. Don't care how clever you are, on the ridge will eventually give you problems. Nailing corrugated steel or fibre cement is a different job altogether.

[him]

Tec screw ALWAYS in the trough. Don't care how clever you are, on the ridge will eventually give you problems. Nailing corrugated steel or fibre cement is a different job altogether.

from my limited experience, and that of my old man and any other rooofer i know it always goes in the ridge, but not made tight.

u r the first i ever heard so strongly about the hollow, would it not gather dirt.

just asking not arguing,

[banjo]

used to do a lot of farm sheds and always put them in the trough straight into the purlin, make sure they are not done over tight or you wont be able to put the plastic caps on and you will have to undo them all again. after a while you get to know how much pressure to put on and they wont let water in

[Courier]

Well,flat roofs were popular in the 70's
Any leaks?,if not I'm flabergasted.

Started leaking in the mid 90's when the 20 year guarantee had run out and the tanalith salt in the purlins had reacted with the underside of the sheet and just left a film of plastic on top.

[Olliedog]

never done it that way before, never will in future either for cattle shed anyway, machinery not likely either. can see where ur coming from with the argument on distortion, but as im sure u know its the man on the drill.

when u would have to nail on a roof where would u put the nail? black rubber washer type nail.

The 'Crown' screw fixings are predominantly used on Fibre Cement sheets, these have replaced the old style nail fixings.
The large rubber washer is large enough to 'shed' water away from the screw hole and start the water on its way down the slope of the corrugation.
The idea is that the fibre cement is more difficult to get a good seal onto and that the valley of the corrugation is near impossible to get a profiled seal.
The fibre cement does not flex as much as steel sheet so you can get a good fixing through the crown, this still requires the right amount of fixing and overdoing it will lead to the sheet cracking, something that wont show until a few years down the line.
When fixing steel sheets, it is the exact opposite and the valley fix is the only way to go.
I was sceptical when I first started but after much research and 100's of jobs later, I am convinced.
Just sheeted 2 cubicle buildings 250m x 32m each and a parlour of 22m x 100m and after all the rain we have just had, not one leak.

[wr.]

from my limited experience, and that of my old man and any other rooofer i know it always goes in the ridge, but not made tight.

u r the first i ever heard so strongly about the hollow, would it not gather dirt.

just asking not arguing,

Carry on if that's your preference but if you talk to the people at Ash & Lacey, they'll tell you that the screws were developed to fix in the valley. I don't want to argue either. Life is too short

[Courier]

Started leaking in the mid 90's when the 20 year guarantee had run out and the tanalith salt in the purlins had reacted with the underside of the sheet and just left a film of plastic on top.

Just to clarify this was on a 88ft run at a fall of 1:80 and the first leaks were where corrosion had eaten away at the steel along the line of the tanalised purlins not specifically at the site of the fixings.

Fixed through the bottom of the corrugation at EVERY purlin .