suggestions on correct procedure in prefab walk-in assembly
Good evening to all.
This is my first post in your forum. I'm a novice HVACR technician just out of technical college. Currently working for a frozen food importer and distributor. I hope to be able to offer some help to other in the near future, but right now just learning the trade.
I'm leading a crew in assembling a prefab walk in freezer. The civil contractor just finished the insulated floor (two layers of 2-inch poliurethane rigid plus concrete slab) and we are currently erecting the walls. We are being very careful in following the instructions included with the walk-in and, though we are keeping a watch on the vertical level of the panels (both front to back and laterally), I can see that the top of the panels are not aligning but rather going a little up, as in a ladder. I guess the concrete slab is not as leveled as promised. My question is: should I keep going with the assembly of the four walls and at the end make an all-around leveling cut at the top, or is it better to begin shimming the walls in order to keep the top aligned ?
Any suggestions welcomed.
I would shim the walls. If you don't the ceiling panels and maybe some of the walls won't align correctly. Then come back with sealant, foam and flashing for the gaps.
"The best preparation for good work tomorrow is to do good work today"
Shim the walls
Shim as you go!!!!!!!!!!!!!! Trying to get it all at the end will not happen. You can't just cut to get it back, your cams won't hit so you won't be able to lock down. If the floor is way out make them fix it!!
Too much shimming will be a problem, especially on freezers without floor panals. If you are having to shim 1/2" or more every panal I would stop and shoot the floor. See how bad it is and have contractor pump it up if nessisary. In the future never assume your floor is good. Always always always shoot the floor before you start and make the fix if nessisary. Good luck.
Floors are almost never ever level. Worst one I came across was a new grocery freezer with display doors. Back of freezer slab was 4" low!! had to have the slab pumped up. Also had a few that had to be jackhammered and redone multiple times. Starting to think level concrete for a box is a lost art. (as well as floor drains that are not higher than floors)
For future reference... always check it. It seems very few boxes can be constructed without some snare. Just last week helped construct 4 good size boxes and on one of them a critical ceiling joint where hangers locked in had 6 out of 8 cam pockets in backwards. I enjoy building boxes but sometimes you need a lot of asprin.
One of the better sets of instruction for erecting a walk-in is from Bally.
Bally Walk-in Installation Manual
A level and even floor is very important, as has been pointed out...and remember, the bigger the box the bigger your problems will be if the floor isn't right.
As mentioned in these instructions, before you begin, it's best to check the floor for level with a transit or a good builder's level. I have used a water level and found it quite handy. It's important to find the highest spot in the floor and and use that as a starting point.
Since your box has no floor panels, you have to anchor the wall panels directly to the floor, so this make it even more critical to have a decent floor to work with.
Pay attention to how you're using the cam locks and the sequence you do them in. I've seen guys set up a wall where even though the floor is good, the panels tend to ride up a little at every joint creating that sawtooth look you describe. Get each one aligned exactly before moving on to the next one.
Some box manufacturers suggest not fully tightening the wall's cam locks until the wall and ceiling panels are in place. This can be helpful as long as you put up and loosely align the wall and ceiling panels together and tighten them up before continuing on to the next ones.
Thank you very much for your time and suggestions. Just two comments:
1. I forgot to tell you that the walk-in is not of the cam-lock (I researched it is a kind of securing device) type but rather of the male/female joints. According to the instructions, the roof just seems to rest on top of the walls. It uses a lot of metal angles, flashings,and caulking, fixed with self-drilling screws for both the corners between walls and the wall-to-roof joints For this reason I thought it might be possible to make an all-around leveling cut after assembling the walls, in case the slab leveling was catasthropic.
2. Forgive me for my ignorance, but what is a water level? I know what a transit is but not very familiar with its use. I'm used to the the level which is more like a long ruler with liquid filled vials on it.
I'm familiar with that type of panel construction but I've never had any real field experience with it. A level floor, proper panel plumb and alignment is still just as important.
As for the water level, here's a link which explains what it is:
You can make one yourself quite easily.