Hi guys, I was just asked to provide material for a small coffered ceiling for a local developer. I'm currently building the cabinetry for this room and so he wants the ceiling woodwork to match the stained rift white oak we're using. I occasionally will mill some custom trim, but I don't do too much installing and I've never done a coffered ceiling so am looking for some guidance.

The basics are stain grade rift white oak in a room roughly 11' x 12'. There will be 4 "beams" with 2 running across the ceiling in either direction. Then a custom crown running the insides with the middle field left painted. Finish carpenters will install all the work. This is an expensive home so I want it to look like it's done right. So I'm wondering how these are typically done…for example, should I run all the stock and have everything stained and finished? Should I try to pre-assemble whole sections that can be pre-finished and installed as a unit, or just run flat material?

thanks for any tips or help you can offer,
JeffD

No way the beams are installed parallel or even square to each other for pre cutting molding. I'm confused at all the other questions. Didn't they tell you what they wanted? If finish carpenters are on site, provide straight stock, and ask them how much overage they want.

Do your trim carpenters a favor -- run a couple of extra sticks and set them aside. If the desperate phone call comes through and they've chumped stuff (or, less likely, found defects that you've missed), you'll be a hero.

I have always tried to bring more work into my shop by proposing we do assembly or sub assembly where prudent. This brings us more work, we increase our reputation as the shop that can build (emphasis on "build") anything, we separate our work from the lumber supplier that just ships mill run stock, we help the carpenters look good (they often need all the help they can get...), and the final product also looks better since we inject better design details. Providing a few extra parts is also a good idea, as Riggles suggests.

We often vary the width of primary and secondary beams, add a soffitt or perimeter beam, and lately have people wanting our stopped chamfers. We stop them with a bit of a carved lamb's tongue, and the parts are distinctive and authentic.

With assembled faux beams we will assemble the 3 sided parts and also send a 3'-4' long assembled part solely for the carpenters to use to cut/scribe to soffitts or wall boards as a trial fit, then cut the real part.

Our job is to satisfy 3 people - owners, builders, and carpenters. And sometimes designers.

We pre-assemble as much as possible with the last end a job site fit. Make the sub assembly that the trim fits over so there are no mistakes about how it was intended. Our sub-assemblies are CNC cut from sheets of MDF or P Bd. Screwed to the ceiling. Setting jigs are provided to make sure they get the best fit possible. Not all finished carpenters are experts.

The crown moldings we send with our store fixtures are done in a similar fashion. Fully assembled, finished and ready to set in place on the top of the fixtures. The crown assemblies/fixtures do not go to the ceiling.

Thanks for the responses guys!

I've been thinking about it over the last week and I think I have a fairly decent idea about how to go about prefabbing them. I'm going to put the ideas on paper and maybe do a small mockup of a section. Then I'll give them 2 options either supply pre-finished stock only, or a full pre-fab ceiling.

My thought is to make the "beam" parts as a U with the bottom of the U having a veneered face. The tops of the U would have cleats to make for easy shimming and attaching to the ceiling. The beams would all be pre-cut and labeled to go in with minimal fuss. Any and all scribe would be done on a "half" beam around the perimeter of the room.

I would then make "boxes" out of 1x stock and have the crown all pre-cut for each box. The outside of the box would have a 3/16" or so rabbet right up to about 1/2" or so of the top. Once the beams are in place each box would slide over the beam until flush with the top of the rabbet. The box would not have to touch the ceiling, again making for easy installation. Then a few screws through the box into the beams and install the precut crown into the boxes covering the screw holes. Leaving the only visible fasteners as the nails for the crown.

Anyway that's my best thought yet on how to do it and make it fairly simple and straightforward for both fabrication and installation…..thoughts???

Jeff

Not knowing the details of your ceiling, i can only tell you what I've done in the past.
Fabbed and finished the beams in the shop and finished all the mouldings. Install all the beams and carefully measure all coffers and assemble the crowns onsite on a bench and install them as a unit, using only a few nails- not brads- on the bottom edge of the crown, away from the corners, to allow them to expand and contract as they will. Brought touch up finish for the few scuffs
I was able to square up the beams and coffers in all but one seriously whacked room where we had to install the crown in place, a tedious job on staging, but necessary to get a good finished product.

I used to be a finish carpenter full time, and have done a lot of these ceiling treatments onsite.

You probably already know most of this, but here are a few things to keep in mind.

The ceiling will never be flat. The wall/ceiling intersection is also almost always out of square by 1/16-3/16," sometimes worse. It is a real pain to scribe a prebuilt, prefinished beam to the walls and ceiling.

One thing we have done is to leave the beams and crown down a few inches from the ceiling and back light them with rope lighting. It looks good and you do not have to worry about scribing anything to the ceiling. We also fit plenty of them to the ceiling, and it is doable, just takes more time.

Trim carpenters do not like building things with pre-finished material. It is too easy to nick and ding when cutting, scribing and installing, plus gluing finished edges together does not work well, nothing can be sanded after assembly, etc.

Trim guys want to cut their own crown. They do do this kind of thing all day everyday, fitting it in out of square rooms with ceilings that are not flat. Precut crown generally has to be re-cut on site anyway.

I would try to talk with the trim guys and see if they have done this kind of work before, or if they have any ideas of how to make the project go as smoothly as possible.

I as well was a full time finish carpenter and have Installed quite a few of these ceilings.

This is how they would show up to me, Plywood beam sides and bottoms, Sides would be dadoed on bottom to accept thickness on bottom panel

1/4 panels for the ceiling, Crown came in full pieces, and a "L" shaped molding to cover the bottom seam

Plywood was mitered and assembled in boxes on the ground then nailed to framing material attached to drywall, crown covered the nails..

Once all boxes were up I would fill the bottoms in, same material went around the perimiter to the walls

"L" shaped molding covered all the bottom seams of the dadoes, then a crown from the wall to the bottom panel around the perimeter.

Everything was pre finished.. Nothing cut to length or pre assembled, every room is out of square to some degree. You can hide that in the perimeter bottom panels