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Yet Another joist question

Postby spytek » Wed Sep 02, 2009 1:16 pm


I'm having some renovation work done on a mid terrace house. The original idea was to replace the old ceilings upstairs with plasterboards using the existing old beams. The builder has removed the old ceilings and is saying the old beams are warped and says its better to replace them.

He has suggested lowering the ceilings slightly and fitting new joist that will be able to support a floor of any future loft conversion. He will fit plasterboards to these joists so in effect, the joist will support a floor and a ceiling.

I'm concerned that if i did fit a floor in the loft in the future then the ceiling might start to show cracks from the movements of the floor above. Am I being overly concerned?

He hasnt told me what type or size of joist he plans to install but says they cost around £60 each. The house is about 5m wide and the price he stated sounds quite high.

Any ideas on what kind of joists are suitable for supporting a floor and ceiling assuming that if i did convert the loft.. it would be for storage and not a living space. Assuming the legth of each joist would be 5m wall to wall.. what size would be suitable and at what spacing between each?

Thanks for your help

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Postby Edpaterson » Mon Sep 07, 2009 8:30 pm


In my Victorian house all of the ceilings, which are lath and plaster are attached to joists which also support the floor above and all the ceilings are in good condition after over 100years - draw your own conclusions.

As to the size of joist required you will be able to get info from a table reproduced in the projects section of this website. Check under joists.

Can't really comment on the costs but with data for the sizes you should be able to check out prices on the web.

Hope that helps

Ed Paterson
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