Building a carport

[Adrian]

HI All

I'm informed that we need a car port This is partly to provide some shelter for the 'new' car (a 1964 Morris Traveller) - partly as an under-cover place to dry the washing on those infrequent days when it's not sunny in Ireland - and partly as a place to store logs for the woodburner.

I've built garages and timber-framed workshops before - but never a carport....

Am I right in assuming that corrugated plastic is the favourite material for the roofing. We're in a fairly exposed location here - so it'd need to be able to stand up to the odd gale or two.

I wondered about screwing the sheeting in place through a (?timber?) batten, to spread the load on the fixings somewhat - don't know if that is a good plan or not ..?

The span of the carport is likely to be 10 - 12ft or so - and possibly

20 - 24ft long. What's a recommended section for the 'roof' timbers - 6" x 2" maybe ? Likewise the upright timbers - maybe 3" x 3" - or something stouter...? Embedded in concrete ? - probably.... Planning on a wooden wall-plate rawlbolted to the wall - maybe joist hangers onto this to take the rafters.... Probably face the exposed timbers up with UPVC to match the existing...

As I say - not done one of these before - would welcome any 'words from the wise'.....

...as long as they don;t include 'combi or isopon'

Many thanks in advance Adrian

[dennis]

Mine is 13ft x 28ft. It uses 38 mm x 147 mm preasure treated timber. It has metal brackets to hold the joists to the wall plates and notches for

50 mm x 50 mm roof supports. The five metal tubes are drilled and screwed to the top brackets so they can't pull out. Its been there for 20 years with no wind damage. The sheets are just held on with normal fixings four rows of five screws per sheet. The slope is so low that water doesn't drip from the ends so a silicon drip bump has been applied.

Last year the bottoms of the poles rusted through so they are now encased in concrete "boots" cast insitu using an old bucket.

HTH.

[chris French]

In message , Adrian writes

it's good if the carport extends over a door to the house, you can get in / out load etc. without getting too wet. I really miss our old one since we moved.

I think the standard fixing is probably enough. There is generally plenty of screws holding it down. The problem with corrugated plastic comes I think, because it gets left on beyond it's lifespan. It gets brittle with age, cracks and can get blown off. That's what had happened to the one at our old house. Maybe Twin/triplewall sheets are stronger?

-might need less support

IIRC the old one (not built by me - but 30 + years old so it had stood the test of time) was say about 4m x 7m or so.

Joists running across the width of it were probably 9x2 (or maybe a bit bigger), fixed at both ends to the wallplate/frame with hangers. As was the outer frame/wall plate. Crosspieces to take the roofing sheet fixings probably in 3x2 - at suitable spacing to give sufficient fixings - maybe every 2 feet?

Supported at the 'far' end by three 2x2 steel posts with brackets welded on the top to fix to the frame. Concreted into the ground. Other than replacing the plastic sheeting and a little bit of rotten timber (it hadn't been maintained very well in it's latter years before we bought the house) and painting it had lasted well.

[Adrian]

HI Dennis

Thanks for the reply

Sounds similar - final dimensions on my carport still to be decided, I have to draw it out to get 'final approval'

About 6" x 1.5" then.... (sorry - can't get my head round metric wood!)

These support the roofing sheets across their width ?

Hadn't thought about metal tubes for the uprights...... scaffolding poles. maybe ?

Obviously got the calculations right then !

OK - maybe I was over-engineering it....

Slope will be greater here - might need to match the sunroom which is on the other end of the house....

Excellent !

Many thanks for your details - given me something to think about Adrian

[Adrian]

I know what you're saying. The carport will go on the end of the house, and the back door is ... er.... on the back of the house - but there's the possibility of roofing over the 4ft gap between the Studio and the house - which would give a completely protected walkway from the carport to the back door...... I think we may end up doing that...

OK - I'm being paranoid then. Could always go for a few moer screws on the more exposed (front) sheets. I did think about twinwall / triplewall - will have to check Irish prices. It's very easy stuff to work with (built an underground greenhouse back in Suffolk, roofed with three massive sheets of the stuff - think it was 7m x 6m total area. Bad news was - the triplewall roofing alone cost more than 1000 sterling ..... - maybe there's some kind of heavy-dury corrugated sheeting that's intended for agricultural purposes....?

The underground greenhouse had rafters at 2m intervals and cross-pieces every 2m also - very strong - you could walk on it (with care !)

OK - so it's 'doable'....

That's about the sort of dimensions I was considering...

Ah - steel posts again..... might be the way forward. Irish Shedman who built the Studio for me does steel fabrication - might be the easiest way..... could always go completely over the top and make the whole thing out of steel, but then you've got to devize some way of fixing the roofing to it...... perhaps steel uprights would be the way to go.....

Many thanks Adrian

[Matty F]

If you are using clear plastic roofing be sure to paint the timber underneath it white, otherwise the timber gets hot in the sun, turns black and melts the roofing.