Bouncy Floor after building work

2 Feb 2007
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United Kingdom
Good Afternoon all, after having a kitchen wall removed and an RSJ inserted(see Pic 1) my sons bedroom floor is very bouncy and cracks are apparent around the skirting(pic 2) where the RSJ and the corner of the bedroom floor meet. My immediate thoughts are that once inserted there is a gap between the floor beams and the RSJ, not being an expert by any means can anyone shed any light on my problems. All comments appreciated.
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Could be any number of reasons, hard to tell now it's all finished and hidden away.
Do you know the spec? Beam size/span, joist depth, noggins or strut spacings?
Were the joists in the bedroom replaced with new?

Likely to be undersized joists or lack of bracing.
If the steel beam has been inserted directly beneath the joists then the steel should sit tight against the joists provided the masonry has been cut back to allow.

If the steel hits the masonry before fitting tight against the joists then you would pack each joist with narrow packers so that the weight of every joist is collected by the beam. Not all joists are the same depth so packing may vary.

There are many things that a builder should do when fitting a beam, sadly, not all of them do.

For example, we will sometimes spread a mortar bed along the beam before offering it up to the masonry, allowing the mortar to squeeze out thus forming a nice tight joint.

Once in place the beams should be wound tight using an acro prop at each end then the pad-stones fitted beneath.
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Don't like the look of that. Could be any number of problems. My advice is have it opened up and checked by somebody that knows what they're doing.

From a contractual point of view you should tell the builder there is a problem and ask them to check the work themselves. If they refuse or maintain there is no problem then you are ok to get somebody else to do it. But tell them what you are doing and give them a final chance to investigate themselves.

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