Rocking house

[ownerbuilder]

We had the old house raised & it now sits on 100mm steel posts with various large steel beams supporting the house. The lower floor external & internal walls have been built, ply bracing added & weatherboard cladding installed, but the house still has a rocking movement when someone walks through the house.

Can anyone suggest how to minimise the "rocking"? We expected the movement to stop once the framework was put up, but it has only slightly subsided. We need to fix the problem before the plastering gets done!

[bystander]

When I built my house which ranges from 1 to 4 mtr off ground, sits on 100mm steel posts also, it moved around a bit prior to installing steel cross braces between posts. Now it doesn't move, its better than the last house we had which was brick on slab. If there is a storm we get no noticeable movement whereas the old place you really felt it as the wind gusted (if thats a real word). Can you possibly fit cross bracing at this stage, even 2-3mm flat steel should help.

[Barry_White]

Like Bystander says if you can put diagonal bracing in running from the bottom of one post to the top of the next post.

The best is 16mm threaded rod which you can buy in 3 metre lengths and join them with threaded rod joiners with turn buckles on one end to put tension on the rods.

Failing that you could use 32mm x 1.2mm strap bracing and tec screw it to the face of the posts with at least 3 wafer teks on each end. tou can also get strap tensioners to tighten it up. If you can't buy them you could make them out of a bit of cold form channel and a bolt like the pic attached.

[womble]

dont know if you can see any of our bracing, 1/4 steel rod welded as cross bracing all under the house to stop movement

[ownerbuilder]

Thanks for your replies.

We had about 10 sets of cross-bracing included when we had the house raised & re-stumped, although the house still had movement even with these. Out of all this bracing, only one set is left after the builder put up the walls. The cross-bracing was meant to be temporary & were welded on the outside of the posts (not between them). The builder knocked out the bracing to be able to keep the walls flat. The plans included lots of ply bracing. Should the ply not do the same job as the steel cross-bracing? If not then I will definitely look into putting back some cross-bracing.

After taking a closer look at the ground level internal walls, the other problem may be that the walls don't have many connecting points to the upper level. I'm also not sure if this would be contributing to the problem.

Any other suggestions from anyone?

[bystander]

I assume your timber framing is placed between the steel posts. As you will appreciate, this is not jambed in tightly, thus only a couple of mils of space allows movement of the upper floor to be magnified. The bracing must be attached to the steel posts. In one internal section of my house I hade to attach steel bracing across the timber framing, it was flat enough not to affect the plastering, thus I imagine you could weld flat steel cross bracing in eachframe section. Also ensure they are fixed where the braces cross.

Hope this helps

[ownerbuilder]

After the building certifier checked out the house frame, he said that the ply bracing wasn't properly connected to the upper floor. After some extra blocks of wood were attached from bracing walls to upper floor joists, there is no more movement. Problem solved!

[BrissyBrew]

owenerbuilding

I have ripped out the internal walls downstairs of my old queensland, upstairs is now like a kids jumping castle.

Can you advise specifically what needed to be done for the plywood cross bracing to be attached to the upper house.

[journeyman Mick]

BrissyBrew,
there's a real good chance that the walls you ripped out were providing at least bracing, if not actual support for the house. Did someone qualified check on the feasibility of removing these walls and/or did you at least get a copy of the house plans to see what the walls were doing? Even a timber stud wall with gyprock lining will provide a degree of bracing.

Mick