Doubled Floor Joist With Another Joist Near

Away from the top and bottom.

Doubled floor joist with another joist near.

Eurocode 5 offers good advice on how this should be done and covers the size of nail or bolt and their location and centres. Usually when a joist gets sistered the new lumber does not span the entire length of the old joist. So instead of having a post run all the way from the roof to the ground it can stop at the double floor joist. Of walls and rim joists.

I was just following the instructions in a diy book. The nail specification used is dependent on the thickness of the joists being used. The purpose of the headers are to transfer the floor load to the adjacent trimmer joists. In a perfect world any floor joist that is cut should have a header installed preferably two and doubled adjacent joists.

In fact most have little perforated knockout holes that can be punched out with the swing of a hammer. You can never ever ever notch or bore through the top or bottom flange or chord. Most new construction uses 2 by 8 lumber for joists although 2 by 6. Holes anywhere in the web area of engineered i joists except within 6 in.

You can drill 1 1 2 in. Through bolting would ve been better. Used twice the number of screws as what it called for. Drill holes with a diameter of no more than one third the depth of the joist staying 2 in.

If you are doubling up floor joists creating trimmers or trimming joists around stairs and chimneys they all need connecting properly so that they can act as a single unit. This allows you to install a supporting post off the double floor joist to hold a second storey or a roof beam. Putting a partition directly over a single joist increases the load on the joist by 71 to 95 it s even worse if the joists were sized for a 30 psf bedroom load. Making double joists yup i think you re right.

Because of this the tail end of the new lumber is not supported. Purchase the type of lumber that matches the width of the existing joist. Holes anywhere in the web. Notching wood and boring rules engineered i beam rules.

The main reason for doubling up floor joists is to double the strength of a single floor joist. You can get away with this on short spans but you re likely to have problems if the span is near the maximum. If i was making beams instead of double joists i would ve put the screws closer to the edge like maybe 1 instead of 2. Measure the width and length of the existing joist.