I'm hanging ultra light 6" MDF crown. Can I cross nail it and not worry too much about hitting studs for support? Also, to avoid a dilemma often talked about on this website, in the situation above can I use 1-3/4" nails to hopefully avoid electrical and water pipes?
(Cabinet and Millwork Installation Forum)
From contributor A:
I wouldn't depend totally on cross nailing for support. Even though it is ultra light, there is enough weight to pull loose if using only cross nailing. It's not too difficult to find the studs and/or ceiling joists and securely fasten it in place. Use cross nailing for additional holding strength, not the only fastening method. If the crown is actually 5-1/4" you can use 16d finish hand drive nails and nail straight through into the plates. This will draw it tight to the wall and ceiling. If it actually is 6", 16's won't be quite long enough to get a good bite into the plate and you should find the studs and joists. I use 2" nails, but 1-3/4" should work provided you are nailing into wood.
I have hung literally miles of ultra light 5-1/4" crown over the last 10 or 12 years using 16's. I only use the nail gun to quickly shoot the crown in place and in the corners where hand nailing would tend to screw up the joint. It really doesn't take much longer doing it this way versus dragging a hose around and searching for studs and joists. The painters like this too since there are fewer nail holes to fill.
Now to your MDF - get a couple tubes of Powergrab made by Loctite. It is a white construction adhesive that goes on like a latex painter's caulk and it is water based. Hit the top and back edge with a thin bead. Just wipe it up quick, within a minute or so - it tacks up fast and harder than caulk. With this stuff you can shoot 1-3/4" 18 gauge brads - minimize the metal you're shooting at pipes or wire, and not worry again about movement or crown pulling away. Any home center will have it near caulk and the liquid nails.
To contributor A: I can't in my wildest dreams imagine putting up crown using hand nails. You must have some fantastic pay scales where you are to afford doing that. Besides, one miss with the hammer and you've ruined a piece of moulding. I will be the first to stand up and say I lost the ability to hand-nail back in the 70's and my thumbs thank me every day.
Comment from contributor G:
I've been doing some trim work (I've been using MDF crown) around the home and have learned quite a bit from books and forums. One technique I've been using for crown moulding is to cut triangles from 2 x 4’s slightly smaller than the crown (when fit against the wall/ceiling). I use Gorilla Glue (or equivalent) on the triangles - although probably overkill - and nail them to the studs and top plates. When I put the crown up I merely nail it to the triangle pieces. This method seems to work quite well. Traditional – no, but still effective.