Thread: Building a Mezzanine loft floor

It would be smarter to sketch it up in a suitable manner with details on it and take it along to the local council and get your suggested spec checked with them.
They are the legal authority on what you can or can not do.

Originally Posted by cobber and co

Hi Everyone,
Just need a bit of advice on timber sizes and joints,
i am looking to build a mezzanine/loft floor space in a old timber church which will be used as a upstairs open kids bedroom, i plan to put the floor along the back wall which is 5.5meters wide and come out 2.4 meters from the back wall, so the floor space would be 5.5 x 2.4 meters.
My plan is to run a ledger beam along the back wall 5.5 meters, and 3 posts with a bearer beam at the front of the floor landing 5.5 meters (the two end posts will be against the side wall and one in the middle) and hang the joists with-in the bearers at 450 centres (rather than sit on top of bearer), then put chipboard flooring and carpet.

My questions are,
1.Would Tassie Oak 190 x 35mm F17 timber be substantial to be used for the ledger,bearer and the joists ? or do i need thicker timber.
Tassie oak is common timber where i live

2. To sit the joists between the bearers, are metal hanger brackets, along with baton screws skewed on a angle through the joist into the bearer and ledger beam strong enough?

Any help or suggestions would be greatly appreciated!

Welcome

you really should be conforming with the BCA

However, 5.5m x 2.4m seems a very odd shape for a room, kids or otherwise
You may want to make it something closer to 3.6 or 4m wide so there's room to move around items of furniture and the like.
also, what about walls or raling between the elevated floor and the rest of the building -- how will that be supported ?

lastly, there's been a spate of balcony collapses recently, what you're describing is a balcony -- please build it properly

Originally Posted by cobber and co

. To sit the joists between the bearers, are metal hanger brackets, along with baton screws skewed on a angle through the joist into the bearer and ledger beam strong enough?

An open kids mezzanine bedroom sounds like a potential nightmare, but that aside, even when painted I reckon those metal brackets look amateurish, especially indoors and angled battons look nearly as bad unless they are countersunk and filled, ie more work.

I would use a 50 mm wide ledger beam (also for the looks, IMHO 35 mm looks cheap) and put the joists on top of that beam and then baton screw from the top. Along the front I would also use a 50 mm wide bearer and tuck the bearer under the joists by 200 - 300 mm and do the same - a lot less mucking about during construction and will be guaranteed to stay up. If you don't want to put the front bearer under the joists, screw a 50 x 100 ledge to the back of a 35 mm thick bearer and screw the joist onto top of that. The bottom of the bearer will then be 85 mm wide and over a 5.5m length it won't look too chunky, in fact it will look quite thin and if it were me I would look at 50 mm for both the bearer and the ledge.

Tip, paint the underside of the chip board before you fix it and then all you will have to do is touch up the scuff marks.