Seating dimensions?

[paulrockliffe]

I'm making a few seats over the winter. A bay window seat, a seat that sits in an alcove and wraps around the corner and a corner seat in my conservatory.

Does anyone have some rough dimensions for me to start from? I'm after something comfortable, but not as deep as a normal sofa, similar dimensions and ergonomics for all of them.

I don't want to just guess things like back angles and find they're not right when I sit down!

Thanks!

 

[custard]

The bible for furniture design is "Human Dimension & Interior Space" by Panero & Zelnick. They have a long chapter on seating, but to whittle it down to a few sentences,

-The back support on comfortable seating should slope back from the vertical by 15 degrees from the vertical, (which is not necessarily the same as from the seat itself), a work chair might be as little as 5 degrees.

-The seat height will obviously vary with the sitter, 360-380mm is a reasonable average to accommodate a wide range of sitters, if it's just for adults this could be bumped up to 410-430mm.

-The seat depth shouldn't exceed about 390-410mm, or most people won't be able to settle themselves against the back rest. Architects call this the "buttock-popliteal length" and get pretty excited about it.

-Ideally the seat itself will slope backwards to stop the sitter sliding off, 3 to 5 degrees seems to work best, but I guess people won't be sitting on a window seat for several hours at a time so horizontal would be okay.

-The centrally position for any lumbar support is about 240-255mm above the seat for most people. If the back of the seat were frame and panel construction a rail centred at this height would add to comfort.

But if Panero & Zelnick don't inspire confidence you can always run a tape measure across a chair that's proven comfortable and work from that.

Good luck!

 

[rafezetter]

The bible for furniture design is "Human Dimension & Interior Space" by Panero & Zelnick. They have a long chapter on seating, but to whittle it down to a few sentences,

-The back support on comfortable seating should slope back from the vertical by 15 degrees from the vertical, (which is not necessarily the same as from the seat itself), a work chair might be as little as 5 degrees.

-The seat height will obviously vary with the sitter, 360-380mm is a reasonable average to accommodate a wide range of sitters, if it's just for adults this could be bumped up to 410-430mm.

-The seat depth shouldn't exceed about 390-410mm, or most people won't be able to settle themselves against the back rest. Architects call this the "buttock-popliteal length" and get pretty excited about it.

-Ideally the seat itself will slope backwards to stop the sitter sliding off, 3 to 5 degrees seems to work best, but I guess people won't be sitting on a window seat for several hours at a time so horizontal would be okay.

-The centrally position for any lumbar support is about 240-255mm above the seat for most people. If the back of the seat were frame and panel construction a rail centred at this height would add to comfort.

But if Panero & Zelnick don't inspire confidence you can always run a tape measure across a chair that's proven comfortable and work from that.

Good luck!

Excellent post custard and has answered some *wonderings* I had about an outdoor lounger / bench thing I plan to make soon.

 

[Paddy Roxburgh]

Very useful information. I have made many seating areas in boats and have never been sure about dimensions. However for me the problem is often compounded by the fact that the sofa seats often double up as a dinning area when a table folds down, ideally they would be at different heights for different purposes

 

[paulrockliffe]

Wow, thank you that's perfect! More than enough info to go off. I measured up my sofa and it matches up to what you describe fairly well. Though it's much deeper than the 390mm to 410mm that you've quoted, I presume those dimensions are based on a more upright sitting position?

On the 3 to 5 degree slope, does that assume no cushions? I'd think you would achieve a drop in the compression of the cushions, and I'm not sure I've every noticed one with that fall built in.

Next bit to weigh up is whether to build the front as one continues panel or whether to curve the seat in the bay, the bay is 2.4m and about 0.9m deep, so I think I can do both depending on how much work I want.

Does anyone have any thoughts, experience, contacts etc for acquiring the appropriate foam and the thickness I should go for? Thinner foam gives more storage underneath, which is one of the main reasons I'm doing these. Don't want to go so thin that it's not comfortable though.

Paddy what you describe is what you experience in a Caravan too, I remember finding it difficult to sit comfortably to eat at the table as a child, especially as if you have people sat opposite you can't bring the table over to you to make things easier.

 

[paulrockliffe]

I measured up properly and did a Sketchup thingy. You'll have to excuse my Sketchupery, I've not used it much and don't really know what I'm doing!

Window Seat 1 by Paul Rockliffe, on Flickr

The sketch includes 100mm of cushion, which leave the seating area 2m wide at the front, 1.1m at the back and 64cm maximum depth. This is the simplest construction, but takes up the most room and is the most imposing. The boss isn't fully on board with the design yet.

I'll try one with a section cut out to reduce the depth and one where the side cushions only wrap around 3 sides.....

 

[Sheffield Tony]

That looks like a useful reference, thanks Custard. The first chair I made was to a Clissett design, and it struck me as being a little on the large side. Perhaps he was a large seated gentleman ? But, its measurements tally welll with the larger sizes for a chair intended just for adults. I've since used slighly smaller dimensions, somewhere as a compromise between Mike Abbott's plans and the Clissett designs, and that seems better to me. So those numbers seem pretty good.