Building Pentagon shaped building frames

[ben2]

Hi

I am looking for some advice. I am about to start building a new Summerhouse/Glamping pod.

The design is basically a pentagon shape - approx. 3 m wide at the base, 4 m wide in the middle and approx. 3 m high. I will need 10 fames to make a 5.4m long pod.

I was planning on using 6" x 2" for the base and the sides, 4" x 2" for the top section to keep the weight down. To joint them I was thinking of using Domino joints (anyone got one for sale?)..then sandwiching the whole thing in 18 mm ply on both sides, including over the joins.

I am using the lightest roof tiles I can find and Celotex insulation, but am nervous the structure will sag in the middle by the time its lined out etc..

Do you think this will work, or do I need to look at a different solution?

Cheers

Mark

 

[PAC1]

A different solution.
I assume you mean pentagon in end elevation.
Whilst Dominoes are good they are not that good. There is simply no way dominoes will hold that structure together for any length of time. The lower uprights will be pushed out and there is nothing to stop them. You would need to brace the structure but probably at a height that would make it uninhabitable.
I think you need to discuss it with a structural engineer.

 

[NickWelford]

I assumed pentagon in floor plan, vertical walls and pentagonal pent roof. Sounds nice, but large, hence the op's question re sag.

 

[mseries]

I picture a pentagon stood up so we have a flat base and an apex roof, like in this picture http://www.wildwooddesigns.uk.com/ The weight of the top part and roof covering will act down on the lower members, naturally I'd want to place a beam across this building at the hip joint level to prevent he sides moving apart, this of course will probably compromise the inner space, and I guess you don't want any beams inside. So you need those joints at the hip to be very strong. Maybe some kind of bridle joined pinned with hefty dowels and maybe also braced on the inside. Just my thoughts, I am no expert and will be interested in other ideas

EDIT, the gallery section on the site I link to has a picture of the frames of their buildings, might help

 

[Fergal]

What about a pentagonal geodesic dome? These are pretty strong and self-supporting. This guy makes them out of 2x1 battens and polycarbonate roof sheets:

https://www.youtube.com/channel/UCL--oB ... tH7drz5Sjw

There's a calculator here to work out how much material you need for a particular dome size and shape:

http://www.domerama.com/calculators/3v- ... alculator/

Cheers

Fergal

 

[RobinBHM]

I think you could make it work.

I wouldn't bother with any joints, I would make it by overlapping timbers and gluing with PU glue and screwing. On the wildwoodesigns gallery there is an image of one being constructed which show it being overlapped at the joints. I would consider using birch ply corner 'gussets' on both sides of each joint. If they are nested on the sheet of 8'0 x 4'0 ply you could probably get a quite few out of one sheet.

Maybe at 1/3 and 2/3 down the building those frames could have some steel plates made and through bolted. The end frames will be rigid, so it will be near the middle that sagging could be an issue.

 

[ben2]

Hi

Thanks for the replies. The shape in the Wildwood designs is pretty much what I want to achieve, but bigger!

I think the idea of overlapping joints and through bolting metal plates in on inner beams would work, and not difficult to do. Also saves buying a Domino...

On the same topic, does anyone know a good source of good but inexpensive patio doors. I know I should make them but time short etc.?

Thanks again for the replies

Mark