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I need to replace the roof sheeting on our carport - it's breaking up with age and has several holes anyway, but at this moment the cavity wall insulation removers are cutting large holes in it to get at the gable wall above...

The structure itself is nothing special - it's over a single car width drive, with the main door into the house below it. Open both ends and the side is a privet hedge with a gap of eighteen inches or so below the gutter, so insulation is irrelevant. On the north of the house so heat isn't a big issue either, and that's also sheltered from the prevailing wind.

We've plenty of drive space in front of the house and rarely put a car under it, but it's covered storage for the trailer and a really useful extra workshop/storage space. It will get bashed when I get careless carrying things around, so impact resistance is important... :ph34r:

So, what's on there at the moment is clear corrugated sheet - PVC I would guess. But - what's the best thing to replace it with? I'd never realised there were so many different types of sheet!

Polycarbonate twin wall might make a cosmetically nicer roof, but doesn't seem to have a particularly good lifespan (10 year warranty, same as corrugated PVC), and as insulation isn't relevant that seems a bit pointless. More PVC sheet would be cheap and do the job - but again isn't long lasting. Then there's GRP (huge variety of prices and specs - looks promising), and polycarbonate corrugated sheet - something like this https://www.building-supplies-online.co.uk/corrapol-stormproof-high-profile-sheets.html

Obviously it would be possible to spend silly money for no real gain, but that said I don't mind spending enough to make sure I'm not doing this job again in a few years.

Guessing there are people on here who actually know what works and what doesn't - what's the best thing to use? 

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I have used the twinwall plastic sheeting. Looks much nicer than the corrugated stuff and more resilient too. You will need to have rafters at the right spacing though to avoid lots of cutting and wastage.

It also needs more fixing rails and seals etc so ends up a fair bit more expensive. Worth it if looks are important though.

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Looks aren't a big deal - the house isn't particularly attractive (it's a bit of an odd place that started out as a small bungalow before multiple extensions), and the current corrugated roof looks perfectly in keeping.

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Well, don't think I can put this one off for long - it's a bit fresh here today and the holes in the roof are getting steadily bigger! Less to get down, I suppose :unsure:

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Will be interested to see what you come up with - I want to put a car port down the side of my house in front of the workshop but the wind exposure concerns me so it would need to be FHD - so to speak!

Does it need to be translucent? A timber deck may make it easier to reinforce.

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Yes, it needs to be translucent - it would cut a lot of natural light from the kitchen and bathroom otherwise.

This really only comes down to what sheeting to use - the frame is already there and barring a couple of bits of timber that could do with replacing (under holes that have clearly been there for some time) it's solid - steel posts and a decent timber roof frame back to a brick house wall. So the sheeting I use will have to be available in sizes that fit the existing framework, because it's not worth making any significant changes to it.

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2 hours ago, Anderzander said:

You can get very thick polycarbonate clear panels cut to size?

https://www.theglazingshop.co.uk/multiwall-polycarbonate-sheets-sheeting.html

That's quite appealing, if only for saving the hassle! I need to measure up the spans, but looks like that could get quite spendy...

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On 5/23/2020 at 8:06 PM, geoffbeaumont said:

That's quite appealing, if only for saving the hassle! I need to measure up the spans, but looks like that could get quite spendy...

You could just cross batten it with roof battens and don't worry about the sheets width.

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This is all on hold at the moment, as we're going to need to knock yet more wholes in the carport to put up scaffolding to replace the felt and cladding on a dormer above it, as well as some more work through the existing holes. 

Unsure what I'll go for - corrugated and multiwall polycarbonate work out similar prices - the carport is 11.3 x 3m, so it's going to be over a grand either way. 

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Our conservatory roof is twinwall plastic sheet, 27 years so far and still going strong.

To save future problems with the dormer would it be possible to put a sloping roof from the front up to the ridge line then slate it even of it is a shallow angle, the alternative would be a fibreglass cap.  Bothe are more expensive than refelting but you will not be facing a replacement in 10 years.

Peter

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18 hours ago, geoffbeaumont said:

This is all on hold at the moment, as we're going to need to knock yet more wholes in the carport to put up scaffolding to replace the felt and cladding on a dormer above it, as well as some more work through the existing holes. 

Unsure what I'll go for - corrugated and multiwall polycarbonate work out similar prices - the carport is 11.3 x 3m, so it's going to be over a grand either way. 

Shop around a bit. I have the polycarb plates on my veranda (7x3m ish), had to replace them last year. DIY and local speciality stores were going to be >1k, found a store online that had them for about €500 delivered.

Make sure you also get the tape to seal the ends.

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I'd factored tape and bars/fixings as appropriate - given that and that I'm looking at getting on for double the area the (online) prices I was looking at don't look bad. I haven't shopped around yet, though.

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The place Anderzander linked is £18.90/m2 (inc VAT) - that compares favourably with €23.15/m2 that your supplier charges for wider sheets (the price goes up if you select a greater width). Used to truck drivers that can't navigate here - most satnavs dump people in the middle or our postcode not at individual properties, so we pretty much always get a phone call to say they're lost...

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The 980mm I have already bows quite a bit, so I definitely wouldn't go wider without supporting it. But I'm sure that's not really a problem on a carport.

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I was wondering whether I'd need to go up to 25mm - guess that answers it! The carport will be at least as bad. The wind can get under it so it needs to be pretty rigid or it'll disintegrate in a storm sooner or later. 

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Bit late on this, but we have a temporaryish lean to covering what is laughably called a patio, its 11m x 5.5m, and I bought GRP corrugated sheet from a company near Foston ? prison. They deal in seconds and end of batches etc. There are so many different profiles though, so make sure there is enough of the same batch (or similar) plus your existing batten spacing has to be considered with the lengths available. I will try and find the phone number.

Covered the lean to for £300, plus some spare, and its very hard to break, unlike the crappy polycarbonate stuff, and has good light transmission, and certainly makes a difference to the temperature underneath it.

The only downside with all these coverings though, is condensation, which will drip if the roof slope is very shallow.

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The really rubbish stuff is PVC, though the polycarbonate ones come in a variety of grades from not much better than PVC up to fairly heavy duty. 

That sounds interesting, if they'll deliver to Lancashire. 

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14 minutes ago, geoffbeaumont said:

The really rubbish stuff is PVC, though the polycarbonate ones come in a variety of grades from not much better than PVC up to fairly heavy duty. 

That sounds interesting, if they'll deliver to Lancashire. 

Stay away  from fiberglass, too. It doesn't support weight well, so if you need to get onto the roof for any reason, you are stuck.

I had a polycarbonate roof over an alley at a previous house, and it is stronger than the equivalent thickness galv/chromadeck sheeting for walking on.

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Well, once the work above is done, I shouldn't really need to go on it for a few decades! We're catching up on long term neglected maintenance and putting right bodgery, but for routine things like clearing the gutters I can just walk across the house roof from the other side.

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