Thread: Timber Subfloor Construction

before any comments, some questions:

What is the flooring: structural sheet flooring or tongue and groove strip flooring.
What finish is on the floor: carpet / tiles / floating floor / polished T&G floor boards
How many rooms & size
What is the external cladding

Hi there,

Thanks for reply,

The floor is tongue and groove with tile finish on top.

this is a veneer construction with blueboard cladding.

The floor sit on top of isolated brick piers and also around the parameter of the structure.

there is 2 bedroom.

Also, the roof is flat with metal roof.

Originally Posted by Bruce23

Hi there,

Thanks for reply,

The floor is tongue and groove with tile finish on top.

this is a veneer construction with blueboard cladding.

The floor sit on top of isolated brick piers and also around the parameter of the structure.

there is 2 bedroom.

Also, the roof is flat with metal roof.

How much clearance have you under the joists at the lowest point or is it almost level ground

Hi rwbuild

On one side its about 400mm and on the other side some part its almost on the ground and some are about 200mm.

I have check some alternative solution for ventilation issue. They can have mechanical ventilation system which can suck the air out from the sub-floor to avoid damp.

But I'm not to sure the Council would except this alternative solution....

The other problem is how do I tire the metal rod to the Bearer and Joist since its already constructed and even so, how could I access to some to some piers to tired it together since the space are quite low.


I think the last resort is to jack the whole structure and build it according to the BCA.

Anyone have any suggestion or come across this issue?

Ive got a feeling your easiest/first solution (without seeing it) is to have it raised and restumped.

You couldn't dig down as then your existing stumps wont be deep enough (and it would be a nightmare!)

Call a restumper/reblocker in to get his opinion.

Good Luck

As this is an addition to an existing house, I presume it is joined on, so raising and restumping would create a whole heap of issues, roofline and floor not level with the rest of the house are the 2 main ones that spring to mind.
From what I can make of the situation I think the best course would be to remove the floor, dig out to the required level and install a steel stump each side of each brick peer. The steel stump will need to be concreted in and bolted to the bearer.
The main thing would be to have the council building inspector have a look at your proposed solutions before you go ahead and do anything.
Best of luck, I don't see a easy solution to this.

It only has to be tied down around the perimeter. It can be re piered to the correct size around the perimeter with temporary support of the external walls, then cut a section of floor out following the tile joints and redo the internal piers again with temporary support or simply beside the existing ones, once this is all done, you will then be able to excavate the ground underneath (all be it very slowly and tedious) by hand with a small demolition drill with a spade bit. You will need an engineer to design and certify the work BEFORE you submit it to council.

A lesson here for everyone, there is no cheap short cut to anything, do it right the first time, its cheaper than rectification

Pull the floor up and pour it in concrete. Better for tiles anyway. What goose would lay bearers and joists at ground level?

Originally Posted by rustynail

Pull the floor up and pour it in concrete. Better for tiles anyway. What goose would lay bearers and joists at ground level?

I agree, but the funny thing is my own house is built just like that.
It would have been built without council approval, however there was no council here until atleast 30 years after the house was built. It is still as sound as a bell with beautiful polished jarrah flooring the like of which you would rarely see.

Yep - I put a new kitchen in a house built back in the 1850's - by convicts, out of mud bricks fired on site in a kiln built from - mud bricks out of the passing creek.

The sash windows were sent out from England on sailing ships and made from english oak it appeared.

The floor was laid on green hand sawn Jarrah joists and bearers, laid direct onto the ground! Also had 5 Inch wide local jarrah floor boards on top of that.

Its had sunk something terrible over the intervening 150 years, like 4 inches over the length of the kitchen benches.

Had to make the cabinets toe rails to suit the fall in the floor... i.e about 150 tall - so 50mm at the high endand 150 at the low end.

Dad being a builder suggested we re do the floor - stump it etc - but the heritage commission people said no way, it HAD to be left as was!.

It was damp under the floor - rabbits were eating the hand made & fired clay bricks away from the outside (don't ask me why - maybe rising damp brought out the salt they wanted or something).... the bricks were really soft - they crumbled if you rubbed them with a finger.

Still it was a lovelly old house despite all the structural issues.

We put in a replacement sash window - for one that had rotted away, but it had to be an exact duplicate of itself and it's matching ones... ended up we used American White oak was the nearest timber we could get to match (they were painted over so no one would have known anyway - but again with the heritage people & their somewhat inflexible rules).

The house wasn't actually listed yet - it was on their list to be listed but required legislation to be listed and every time the heritage people gave the owner grief about maintenance and improvements etc - he would tell them that coz it hadn't been listed yet - and they were being so difficult he would just demolish it and build a new house and they could get stuffed... so they would let him do certain things...

If you can avoid it, don't ever list a house...once listed they have control over what you can and can not do - but they don't PAY anything for the restrictions they impose on you in your own house on your own land - they canm tell you it has to be pained with moon dust and unicorn urine if they have a mind too ...and it's YOUR cost to comply.

I'm all for preserving our heritage, but sometimes the heritage people can be officious pedants playing with other peoples $.

But yes - bearers and joists direct on the ground - that's apparently how it was done before stumping...

Only time I've ever seen it tho!.

I think the Drake Brockmans or some of those early settlers had it built...



Called "Bidelia House" or some such I think from memory on the Vasse hwy at Barlee Brook - Carlotta, between Nannup and Pemberton in WA's southwest. Can't see much of it from the hwy these days on Google Earth street view, but the old barn out the back was where they lived and built the house - I THINK it might have even been where the bricks were hand fired out of clay from the Barlee Brook that runs past the back of the barn... great little trout stream from memory.

Glad to see its still standing at least.