First post and beam timber frame - mezzanine floor

Hello all!

My names Elliott and I'm a furniture maker down in Bournemouth, UK and I'm just about to move to a bigger workspace (woohoo!)

A couple of friends are joining me to work and we've secured an industrial unit that's around 800sqft, but the best thing about it is is 6m high! So to take advantage of this we would love to put in a mezzanine floor to to give us an extra half of space. The rough size of the workshop is 8mx8m so we want to put in a mezzanine that's 8mx4m.

Of course it's easy to go and buy a steel one, but they dont half look boring! We are looking to expand into doing some traditional post and beam framing as part of our overall offer so would love to use this as a chance to create an exhibition piece for the workshop - for practice and for when clients come by.

So here's the design of the frame, all of this design is based on knowledge read from Jack Sobon's wonderful book (https://www.amazon.co.uk/Timber-Frame-C ... 0882663658)

Ok so heres the run down:

DETAILS:

6"x6" timbers on the post, beams and cross beams,

Then 8"x2" floor joists

Posts are 4m apart in all directions so the joists span 4m, joinery is all traditional post and beam, so mostly mortise and tenon, through tenons where possible,

Long beams Are scarfed jointed over the central brace (as per my reading in my timber frame book) then the posts have tenons on the top into the long beam,

Cross braces are placed 6" below the top beam to space out the mortises, to stagger the joint so I'm not taking out too much wood in one point (again as per reading from my timber frame book)

All mortise and tenons are let in to the wood with additional shoulders for strength, same for the braces, everything pegged wit oak of course

Al the beams will be Fresh cut Douglas fir and the floor joists will be standard cArcassing.

And the top will be a simple 18mm chipboard,

The sketchups are attached and the main thing that's concerning me is how to place the floor joists in they arnt done like this in the main drawing, just In a close up) I was thinking letting them in 1" (25mm) and having them run over the top plates - I think this will be strong and height isn't an issue

Thanks for your help!

Hey Elliot, with design you will have to watch the loading, in a shop environment it would be better to over build (who knows what the loading will be over time.) In any case, 6 x 6 beams will likely not be able to carry the load. I would look at the capacity of 6 x 10's as a better option. On the scarf detail, I would extend the under scarfed beam so it safely captures the brace end. The scarf detail as drawn will have a separating reaction force imparted by the brace to the over scarfed beam. I'll vote for the joist over shooting the beam.

Thanks so much for your reply Roger,

Unfortunately we are limited to the 6x6 posts as its all we can source locally,

It will be a floor for a small sewing workshop - so nothing like a woodworking shop load,

For the scarf joint, is that you mean here? Thanks again!

You have the scarf idea, however you will need to extend farther in order to give more wood behind the peg. 6 x 6 should work for posts. I am concerned over the beams capacity.

Two options if you cannot obtain larger timber.

1. Shorten the span by adding another post.
2. Assemble built up beams from 2 x 10 lumber.

Consult local building code for loading standards, then design the structure.

Thanks a lot Roger, I'll give it a redesign!

Elliott

So do you think just one more cross beam section added would work? Or would it be better to run the joists the other way? (as the long joists running front to back are still on a 4m (12ft) span, which the 8x2's are rated for, I think! Attached is a drawing

Sorry attached a version with some measurements (imperial!)

The last drawing has the basic idea. It passes my looks good test, which however is not a substitute for load calculation. Adjust the scarf position.

Best wishes

Thank you again Roger, are the joists running in the correct direction? Yeah I havent redrawn the scarf yet!

As there will still be 6"x6" running back over the 11ft (inline with teh joists)

And when you say load calculation - does that mean I should get in touch with a structural engineer?

Another option would be to add a third bent/wall midspan under the joists.

Since I have no idea about building, engineering standards and the approval process in the UK, I can offer no advice about requirements but Prudence and her virtuous sisters say look for local advice before building.

Appreciate it Roger

Ill ring the Sawmill tomorrow to see if I can convince them to get me some 6x10's.. if I replace all the beams with those I should be able to use the original 6 post design

Updated my drawing here, increased the span of the braces too, still 6 foot underneath the bottom of them,

all beams 6x10 and posts 6x6,

Thanks all for input

Ah i missed off the rear braces.. imagine they are there!

Ok so I've done the usual think on it overnight (always works quite well)

So if I were not able to get hold of 6x10 in fresh cut doug fir, could I then go for normal off the shelf KD 2x10 (like you said) with the eased edges like you get with normal carcassing then glue them together to make up the 6x10 would that be viable? I dont want to see metal fasteners, so could I just glue laminate them then buzz through some 5 1/2 screws from the back side?

And would this pose any issue working with fresh cut wood, fresh cut braces but KD beams? I take it as the beams are already dry I just cut the tenons a little short so they can shrink a little?

Thanks!

Elliott

Ok so I've been speaking to the my work buddies who im building this with, and the saw mill want quite a lot of cash for the 6x10'!

We are looking to go with the adding the extra bent option,

So I've redrawn it all up with resized braces and everything drawn as it will be built

All posts and beams are 6"x6" and the floor joists are 8"x2"

Let me know what you think of the plan,

Thanks!

Hi Elliot,

I believe an added bent is but one option.

Another is to remove the oblique braces, and either use a Corbeling system and/or Truss System in concert with the Corbels. As such even a 100 mm square timber could suffice, and have seen similar with timbers as small as 75mm x 100mm when fashioned into a timber Truss Assembly...

I sent a PM as well to you with additional contact information...

Cheers,

j