How To Fix Flat Roof Joists To Wall Plate

To fix the joists and rafters down on to the wall plates they should be toe or skew nailed to the top plate like below.

How to fix flat roof joists to wall plate.

Mark the installation location for each joist along the wall plate. Set out the ceiling joists onto the wall plates the ceiling joists are installed before the rafters as they will stop the roof spreading and also give something for you to lay planks across to stand on when building the roof. By fixing the joists to the wall plates and securing the wall plate with vertical holding down straps at least 1m long and 30mm x 2 5mm in cross section at 2 0m centres. If the wall plate of the flat roof is level with the wall plate of the existing house can you make the two wall plates the same height then you will need to strip off some roof tiles and run the new joists through butting and fixing them up to either the roof rafter or the ceiling joist on top of the house wall plate.

Make sure that the roof truss is aligned properly on each side of the wall plates. Place the bottom of the truss onto the wall plate aligning the left edge of the truss with the edge marks placed on the wall plate for alignment. For example when setting trusses you will rest each of the two ends of the truss onto opposite walls which have wall plates at the top of each wall. Wall plates are to be fixed to masonery using hardened nails 4mm in diameter x 75mm long or 50mm long wood screws if fixed into timber.

Insert a 6 cm 3 1 2 inch nail through the truss base where it sets on the wall plate. Install steel joist hangers at each mark. Pump your rawl plug chemical resin into the holes this stuff sets very quickly so once the resin is in place your bars in at the correct length id suggest marking your timber first at 600mm centers and fix the two ends securely first. Face fixed and face fixed wrap over hangers can also have the flanges through which the fixing holes are drilled either showing either side of the hanger or concealed where they are bent over to be only visible when there is no joist in the hanger.

Start at one end of the wall so that the first joist is flush with the walls which run parallel to the joists.