Thread: New timber floor + subfloor for 1st floor of terrace. Help needed

To be honest, I would consider getting an engineer in to spec that. If you are putting it through council, they will almost certainly want engineering details for it. If you are not, then for piece of mind alone, I'd still do it.

Originally Posted by Carved Up!

We are however lowering the floor by about 1 metre

Wow a metre. You must have really high ceilings!

Sorry I don't have an answer to qour query, although the advice of the silent one sounds worth taking.

Ditto to the above, don't even consider using this forum alone to get your answer. Get an engineer and or draftsmen to do the plans.

As I used the I joists in my house I would highly recommend them, they are light, and once down on level bearers they are true and straight, big spans. In the end you would be mad to go with anything else other than engineered joists wether they are the laminated I joists(lots of different brands) or posi struts or any of the other products out there. In the end it comes down to price and wether or not you want to run pipes, wiring or ducting through the floor, if so I would go with a product such as posi struts where you dont have to drill holes in the joists. If you dont need to run anything through them them the multitude of I joists would be the way to go.

The building is heritage listed and we have plans in council and while I am waiting for the approval if it ever eventuates I thought I would do a bit of investigating.

The ceilings are fairly high however the reason we are dropping the floor is because we are also .... in the not to distant future building a second floor with a setback roof projecting above the existing parapett.

I am waiting for what seems like an eternity and I thought that while I wait I may as well enquire as to the process involved. If anyone has had a similar experience and if you care to share that would be great .

Love the idea of squeezing in a second storey behind the parapet walls! The best way to anchor the joists is generally joist hangers on the ends if you are attaching them to a wooden ledger. I would also consider using steel posts as stumps and steel angle chemically anchored to the walls as the ledger. Mechanical anchors generally don't grip well in old masonry and the compressive forces can destroy bricks. 12mm threaded rod anchors every 600mm should be enough.

Cheers
Pulse

As pulse has suggested, chemical anchors would be the go or "frame anchors" by hilti or silmar. If the brick work is a bit old and starting to crumble you may have to build a new dwarf wall on the existing footing to take you I beams.

What amount of clearance do you have from the sub-soil to the under side your new proppossed floor level. And what are the room sizes so that i can give you a rough beam size.

As your structer is load bearing are you only taking the floor load or is there any other load bearing walls for your new extension

Originally Posted by Carved Up!

The building is heritage listed....

You are lowering the ceiling heights on a heritage listed building - hmmm??

Originally Posted by dai sensei

You are lowering the ceiling heights on a heritage listed building - hmmm??

I know its a bit hmmm, but the floor remains the same height on the facade then it drops approximately 800mm a couple of metres back. After consultation with our heritage architect and the councils heritage architect it was the most acceptable solution..... a trade off ...... to limit the exposure of the proposed 2nd floor above the parapett.

The ground floor is a shop of which very little remains of the original heritage components except for the front facade which will remain intact. A couple years ago we had to replace the front timber beam with a steel beam because the termites had feasted on the timber. Also just a couple of months ago, one of the fluro light fittings in the shop had hundreds of white ants, many of them with wings. I removed a piece of the false ceiling and sprayed the hell out of them. The next day the plastic cover was sagging under the weight of the dead bastards. I cant wait to hear back from the council hopefully with the approval cause Im worried the the Units residents are going to come crashing through into the shop.


I was wondering how chemical masonary anchors work. Does anyone have any info about them? :confused:

Originally Posted by Gaza

As pulse has suggested, chemical anchors would be the go or "frame anchors" by hilti or silmar. If the brick work is a bit old and starting to crumble you may have to build a new dwarf wall on the existing footing to take you I beams.

What amount of clearance do you have from the sub-soil to the under side your new proppossed floor level(((Its a new 1st floor and the distance would range from approx 3m-4m))) . And what are the room sizes so that i can give you a rough beam size.

As your structer is load bearing are you only taking the floor load or is there any other load bearing walls for your new extension

The joists span 4m from wall to wall. One of the walls is a party wall, the other is double brick(no gap) and is exposed to the elements. We are hoping to anchor the new 1st floor into the existing walls with minimal impact to the lower floor area including the subfloor (there is a slight slope on the land so the front of the building is flush with ground level however the back has close to a metre clearance so I imagine the crawl space starts off roomy and progressively diminishes . The floor will only be taking its own load and the space with be open plan with no other structures supported except a bathroom and kitchen with minimal plasterboard partitions.

The bricks are in very good condition however the mortar is that crumbly sand and lime but quite well preserved due to being covered by render and paint for the last 100 years or so.

Most chemical anchors come in 2 parts that mix as they are squeezed from the tube. Sika has one for sale at bunnings that will fit it a standard cartridge gun. Ramset has several types, chemset 101 also fits in the gun.

The best type is made of polymethylmethacrylate, which is not adhesive in itself but sets and locks in to the hole. A 12mm threaded rod needs at least a 14 mm hole that is really clean and free of dust.

The ramset website has all the info you need. Some people also use the chemical anchors with mechanical anchors but that seems a bit over the top.

Cheers
Pulse

Thanks for the info everyone!