Reinforcing Floor Joists For Loft Conversion

How to reinforce an attic floor with sister joists.

Reinforcing floor joists for loft conversion.

Clear the joist spaces. There are many ways of altering roof structures for loft conversions but they all have one common element the ceiling joists will almost certainly be inadequate as floor joists. Clearing the loft area of all debris insulation struts and temporary boards to expose the ceiling boards. 6 loft conv rev 2 2007 support to loadbearing elements transferred from the roof partitions and the new floor.

I suspect that the depth of the loft floor rafters are only 90mm. There is a 1 2 plywood sub floor on top of the joists. Each joist is connected by a vertical 2x4 to the roof rafter above it positioned about 4 from the wall. Loft conversions can i just lay loft boards down on my joists or will i need reinforcement on the joists.

The loft room will also have to be separated by a fire door either at the top or bottom of the new stairs. The new floor joists of your loft conversion will need to offer at least 30 minutes worth of fire protection which could mean replastering the ceilings in those first floor rooms below. Pull out all insulation and any debris from all of the joist spaces so you can see the full length of each joist including where it meets the exterior walls. This means that new floor joists are fitted alongside them slightly raised above the ceiling plasterboard to avoid contact with it.

The joists span 20 and are 16 on center. A basic floor system is installed in about 10 stages from preparation to boarding the floor. Also remove any blocking or bridging between the joists as applicable. 3 3 in the majority of instances the existing ceiling joist member will be inadequate for the imposed loadings from the new floor construction.