Got a call today from a client I did an inspection for in July saying she had a crown in her living room floor that had never been there. I went over and sure enough there is a small crown in the middle of her floor. I went into the crawlspace to see If I could determine the cause. Everything in the crowned area looked fine from the crawl. Foundation, floor joists, sub flooring was tight to the floor joists. I did notice that she had not closed her vents for the winter. Could the cold air in the crawlspace cause the floor joists to lift up simular to truss uplift in attics? I have never seen this before. I would appriciate any feed back. Has anyone ran acrossed this in the past? Thanks, Stan
Is it hardwood or laminate flooring? Floating floors can swell and do that, caused by not enough expansion room at the walls. Doesn’t mean the subfloor is moving. If it’s carpet flooring, I don’t have a clue. 
John Kogel
www.allsafehome.ca
Living room is carpeted.
Thats called a “raised joist”
It usually occurs in a new home when a 2x joist drys out and gets a “crook”.
A bow would be sideways, a crooked board would go up or down usually more in the center of the joist.
Its always possible that the joists on either side went down and left this one at its normal position which would then look higher.
No way to blame it on the venting, its just one of the characteristics of lumber that shows up sometimes.
Wood warps, fact of nature, if the crown is severe enough relief cutting and sistering may be a course of action. This would have to be an approved design as I’m not there to tell if this would be a feasible or practical fix, but I’ve done this successfully.
hth
- What types of joists were used- conventional or engineered? Engineered joists move very little and conventional joists might lose 1/4" in width as they dry but seldom bow or twist once installed.
- Do they lap on a structural beam down the center or span the entire floor? If they lap, settling perimeter foundation or heaving posts under a beam may be the cause.
- Was there any give apparent when you bounced on it or was it solid? In other workds, is the framing bowing or is it the floor-covering material?
- How old is the home. Many home foundations will settle over many years, Especially older homes
- Any expansive soil in your area?
Was the crown uniform along its long axis?
1- Conventional
2- Yes
3- No
4- 15 years old
5- No
The crown is present in the middle of the room only.
This is there first winter in the home, they are going to see if it goes away when the weather warms up in the spring. Stan
The situations in older homes or homes that are not new that I’ve seen have been caused by foundation settling around the perimeter over time. Soince the floor didn’t appear spongy it sounds as though the problem is with the framing, not the floor-covering material.
Typically, since the posts (or post) supporting the center girder on which the joists lap have less exposure to moisture (due to their location in the middle of the crawlspace or basement) the girder maintains its elevation as the perimeter foundation settles to some degree. This creates the crown.
This would be especially suspect if the the girder was two beams which butted each other above a single central post, since the high spot was in the center. Was the high spot directly above a post?
No. The crown is approx. half way between the outer foundation wall and the main support beam that runs down the middle of the home.
I have this in my own home every winter It is the flooring i believe In the spring it goes away , my home is 50 so i do not get to excited . i have checked and checked everything looks fine down in the dark depths of my crawl space. I have hardwood