Timber frame footings.

[Screech20]

Hey guys.

I’m currently in the early stages of planning my rear extension, of which I will be tackling most of the work myself.

Being timber frame, I’ve been looking for ideas on how the footings and getting out if the ground will work but can’t much info on it.

Please excuse my very poor drawing, I had to jot down my thinking and it’s all I’ve got on me right now!

Am I on the right tracks or completely out?

Thanks!

 

[^woody^]

Basic principle is ok. You need to work on the detailing.

The frame would sit at floor level.

 

[Screech20]

Thanks woody.

Yes, that was very rough on the only bit of spare paper I had in my van and had to hit it down quickly before I forgot it!

Will draw it up on the computer and see what it looks like.


Thanks.

 

[freddiemercurystwin]

 

[Screech20]

View attachment 147297

What’s that built up from, behind the brick course?

 

[Footsoldier888]

It is block.

Just to clarify your drawing, the frame sits on the inner leaf of the wall, with your render finish on the outer leaf. Timber frame is just like a brick and block house until you get to the soleplate, you can even use strip foundations.

The real difference between timber frame and brick is the foundations need to be super level and square, I think it is a 5mm tolerance over the whole foundation including the diagonals. I have read it is a difficult trick to pull off if you haven't set out and laid foundations before.

 

[Screech20]

So there’s no cavity below dpc in that situation?

In my drawing I’ve got the frame on the outter leaf, and then battens and rendered cement board, which would end up overhanging.
Too much overhang isn’t ideal, any other suggestions appreciated

Thanks

 

[Screech20]

Here a better idea of my earlier thinking.

Now I look at it, does the inner leaf create a thermal bridge? Do I even need it at all?

Thanks

 

[^woody^]

Why build cavity footings for a non cavity wall?

 

[Screech20]

Exactly my thinking now that I’ve drawn it and looking at it.
Just can’t seem to find any examples, unless I’m searching the wrong thing ‍

 

[tomfe]

Freddie has already posted your answer.

 

[Notch7]

So there’s no cavity below dpc in that situation?

In my drawing I’ve got the frame on the outter leaf, and then battens and rendered cement board, which would end up overhanging.
Too much overhang isn’t ideal, any other suggestions appreciated

Thanks

You could have a small cavity, for damp purposes so you have a cavity continuing below ffl.

If you wantnto improve insulation, uou could have pir in between studs and pir outside. That would allow you to have continuous insulation with no thermal bridging or gaps at studs. Also the increased depth would allow you to build on inner wall and have, say a 50mm cavity.

Brickwork stops at dpc usually.

I would think your studwork will need cladding with structural ply or osb for strength, especially lateral stability.

If your in between insulation leaves a space on the inside, that could becom a service void for electrics. If you have enough gap so the cables are at leastb50mm back from the outer face of the plasterboard, the cables would then be in a safe zone and can run in all directions.

Vapour barrier is required internally.

Insect mesh is needed to close off cavity behind renderboard (plastic soffit mesh).

 

[Notch7]

Your drawing needs a little alteration: the blockwork finishes at concrete oversite level and floor celetex runs over it.

As above, you dont need a cavity.

You need any insulation in cavity below ffl level -see floor insulation note above.

 

[pilsbury]

Sorry to back track, but why are you going timber framed route rather than traditional brick/block or block/block rendered cavity wall?

 

[Screech20]

Sorry to back track, but why are you going timber framed route rather than traditional brick/block or block/block rendered cavity wall?

Speed and workability. I’ve worked with timber a lot more than I have than bricks. Plus I can get a lot these materials through work

Cheers