Floor joists

[Reggie Greene]

I am replacing some floor joists in my son's house. It was built in 1955 so the new joists I am buying are not as tall,by about a 1/4 inch. There are 18 joists and I am only having to replace 9 of them due to water damage. What do I do about the hieght difference?

[Jerry Peck]

Shim the ends of the new joists that 1/4" or so such that their top edge is even with the top edge of the old joists ... unless the old joists have sagged, in which case you may want to consider installing new joists next to the old joists which are to remain - making sure all tops of the joists are at the same level.

[Wayne Carlisle]

Another note...on the new joists make sure the "crown" is up.

The crown is the upward arch you see when you look down its narrowest edge. Some lumber may be straight and hard to see the crown but most lumber has a crown.

If you install the joists with the crown down then it will seem like the floor is sagging.