Garden room Flat roof Span

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Danny

Danny

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Hello all :D

I am just drawing up plans for my garden room...

The dimensions are 7meteres wide by 5 meters deep....

I want to do a warm roof as this room will be my office and so I feel this is the best option...

The trouble is the roof span is 5m and the span tables say I need to use 2x8 timbers. That is massive timber because I want to do a warm roof it makes the roof depth huge....

I cant see any tables for doubling up timbers...

I have looked at putting a steel half way to break the span distance but that seems over kill

Danny

PS I could just pay a structural engineer but for the rest of the build its straightforward
 
Just for potential snow load but ain’t the climate getting warmer? probably cheaper than wood to get entire roof steel
 
Monkey Boy said:
Just for potential snow load but ain’t the climate getting warmer? probably cheaper than wood to get entire roof steel
Click to expand...

I have looked at building teh whole thing out of lightweight steel but companies seem to only supply it in complete panels which is great other than I dont have rear access....
 
Timber I joists have a long span , check spec?
Or girder midway for normal joists span

Or do you mean rafters ?
 
Danny said:
Hello all :D

I am just drawing up plans for my garden room...

The dimensions are 7meteres wide by 5 meters deep....

I want to do a warm roof as this room will be my office and so I feel this is the best option...

The trouble is the roof span is 5m and the span tables say I need to use 2x8 timbers. That is massive timber because I want to do a warm roof it makes the roof depth huge....

I cant see any tables for doubling up timbers...

I have looked at putting a steel half way to break the span distance but that seems over kill

Danny

PS I could just pay a structural engineer but for the rest of the build its straightforward
Click to expand...
Looks like a structural engineer is the way forward.

If you get to an inspection stage the building inspector might help you out.

The guy on IOMwas brilliant.
 
Danny said:
Hello all :D

I am just drawing up plans for my garden room...

The dimensions are 7meteres wide by 5 meters deep....

I want to do a warm roof as this room will be my office and so I feel this is the best option...

The trouble is the roof span is 5m and the span tables say I need to use 2x8 timbers. That is massive timber because I want to do a warm roof it makes the roof depth huge....

I cant see any tables for doubling up timbers...

I have looked at putting a steel half way to break the span distance but that seems over kill

Danny

PS I could just pay a structural engineer but for the rest of the build its straightforward
Click to expand...
Sounds like you have mixed up with swimming pool plans
 
ive used 8x2s over 5m. chucked furrings on yop for a slope.

doubling up will be mega money.

maybe a pozi joist be more economical

other option put a masonry wall internal as a support?
 
Engineered joist from pas quills - they will calc for a full span - might have to be 350 centres & use a strong back midway.
 
Dansouthcoast84 said:
ive used 8x2s over 5m. chucked furrings on yop for a slope.

doubling up will be mega money.

maybe a pozi joist be more economical

other option put a masonry wall internal as a support?
Click to expand...

dont want a wall halfway to be honest :D

still makes for a massive depth roof with 8x2 :/
 
@Danny for fucksake stop over complicating things. Put the 8 x 2's on and be done with it. No one, including yourself, will care about the depth of the roof once it's done finished.
 
Danny said:
dont want a wall halfway to be honest :D

still makes for a massive depth roof with 8x2 :/
Click to expand...
go 2.3m high to ceiling height thus giving you 100mm for insulation.

otherwise go 2.4 then by time you insulate between amd 50mm overlay yoir pretty much same height.


or reduce timbersize to 6x2 and rsj through middle
 
If I recall height is measured at the boundary side, 5m is a long way, but, you could use an isometric truss rafter with the high end at the front furthest from the boundary.
This improves the drainage and longevity of the roof finish and, if you want, you can have some high level glazing on the steeper side away from the boundary.
Another alternative is to use steels/plates with wood bolted thru the web or vice versa, called a Flitch beam, used to be common and reduces the depth considerably. I think this is actually going to give you the better answer. You tube link, 1 of 2, re garden office roofs;
 
Brimstone said:
If I recall height is measured at the boundary side, 5m is a long way, but, you could use an isometric truss rafter with the high end at the front furthest from the boundary.
This improves the drainage and longevity of the roof finish and, if you want, you can have some high level glazing on the steeper side away from the boundary.
Another alternative is to use steels/plates with wood bolted thru the web or vice versa, called a Flitch beam, used to be common and reduces the depth considerably. I think this is actually going to give you the better answer. You tube link, 1 of 2, re garden office roofs;
Click to expand...

Ah Yes a flitch beam I have used these before!!!

what a good idea...

I was looking a flitch been to go the full 7m width at the front of the building so that I have options to add better doors and no risk of sagging etc..... but adding another 2 so splitting the roof into 3 going the 5m distance back would drop my span to 2.2m which means my timber thickness can be around 4x2 :D

nice ;D

knew this place would get there in the end
 
Danny said:
Hello all :D

I am just drawing up plans for my garden room...

The dimensions are 7meteres wide by 5 meters deep....

I want to do a warm roof as this room will be my office and so I feel this is the best option...

The trouble is the roof span is 5m and the span tables say I need to use 2x8 timbers. That is massive timber because I want to do a warm roof it makes the roof depth huge....

I cant see any tables for doubling up timbers...

I have looked at putting a steel half way to break the span distance but that seems over kill

Danny

PS I could just pay a structural engineer but for the rest of the build its straightforward read more.....
Click to expand...
Hi, I'm after a bit of advice on this build if possible. It's the roof, can I go with 44 x 95 finished C24 instead for the roof joists (perhaps at 400 or 450 centers?

I've possibly dropped a spheroid and had the C18 70x44 stud delivered now I'm thinking I should have gone 95x44 to better support the planned 145 C24 joists..?

I'd appreciate any advice and guidance, thank you.
 
Danny said:
Hello all :D

I am just drawing up plans for my garden room...

The dimensions are 7meteres wide by 5 meters deep....

I want to do a warm roof as this room will be my office and so I feel this is the best option...

The trouble is the roof span is 5m and the span tables say I need to use 2x8 timbers. That is massive timber because I want to do a warm roof it makes the roof depth huge....

I cant see any tables for doubling up timbers...

I have looked at putting a steel half way to break the span distance but that seems over kill

Danny

PS I could just pay a structural engineer but for the rest of the build its straightforward
Click to expand...
How can you reduce the size of the roof timbers for a 5m span in a warm roof design without using massive beams or steel supports?
 
Jhonsteve111 said:
Flitch Beams could be a good solution for this but except flitch Beams what could be the solution?
Click to expand...
As my suggestion to Danny above. Change it from a flat roof to a single or double slope to be able to introduce some form of truss rafter. The usual problem is trying to duck under Planning & Building Regs height stipulations. Of course, you could reduce the internal height from 2.4 to say 2.3 or 2.2m?
Stefanrobin's sizes are way too small. Even if it looks ok and flat when built it will sag and dish, so ending up with a paddling pool on the roof. Mate of mine had that happen to his, 3 storeys up and covered in slime, water doesn't get to the gutters until it overflows the roof.
Random thought - Concrete beams might, just might, work. but pretty impractical.
 
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