Posted on February 23, 2008 by brevell


When we are making a corner cornice where two boards come together and wrap around the corner with no returns the most effective joint will not allow any light to peep through. If the measurements from the corner to as far out as you want the cornice to go are 125″ on the left side and 72″ on the right side we will make the top board (dust cover) 124 1/4″ because it fits inside the left return which is 1/2″ wide plywood and we want a little wiggle room (1/4″) on the right end. The dust cover on the right side board is the same size as the face board minus 1/2″ because it fits inside the right return. How do we figure the size of the face boards? If you look at the photos you will see that the right side board butts up against the dust cover of the left side board. Let’s say we have 6″ returns so our dust cover board is 5 1/2″ wide. If the customer wants the right side cornice to extend 72″ from the corner we would make the face board 72″-5 1/2″ = 66 1/2″. The face board on the left side will but up against the finished face of the right side which is 6″ deep. With the left side measure 125″ from corner to outside left return we will make the face board 125″-6″= 119″. Notice from the photos there is about 1/4″ between the inside end of the left side dust cover and the wall at the corner. This is the ‘wiggle room’ we need so the joint is nice and tight.
Filed under: 1, Corners and Bays, Cornice Boards | Leave a comment »
Posted on February 22, 2008 by brevell



When interior designers ask us to build upholstered cornice boards that are over 110″ long we need a way to make them strong so they won’t break while being transported to the customer’s home. Plywood comes in 96″ long sheets so if we have an order for a cornice board 185″ long and 12″ high we could just edge join two boards-one 96″x12″ board to another board 89″x12″ with a joint roughly in the center. But that would be the weakest point of the board if two people each lifted an end. A much stronger solution is to cut five boards 2@96″x6″, 2@ 44.5″x6″ and one at 89″x6″. The two 44.5″ pieces would be attached at each end of a 96″ piece producing a board 185″x6″ and this would be used for the bottom half of the face. The other 96″ piece would be joined to the 89″ piece producing another 185″x6″ piece which would be used for the top half of the face. Then the two 6″ sections would be joined together to make a 185″x12″ board. Most cornice boards have a dust cap or top board that lays on L-brackets for when the cornice is installed. The joint(s) in the dust cap boards would be located at least a foot away from the joints in the top face board. By alternating our joints this way we can build cornice boards up to 20 feet long with very little loss of strength.
The five boards are laid out on a table to make sure we have made the bottom three 6″ boards the same length as the top two 6″ boards. Next we measure to make sure they add up to 185″. There is a good old saying “measure twice and cut once”. When we are sure the five boards will make one board 185″x12″ we lay a long straightedge on top of the boards at the long edge to make sure the joined boards will be nice and straight (we can’t just assume we made perfect 90 degree cuts so the straightedge shows us where we have to adjust the lineup). We will first staple all the boards together on one side, then flip the whole thing over and staple them together on the other side. Then we hammer in aluminum edge joiners (dog ears) every two to three feet along the horizontal middle joint and spaced every two to three inches along the vertical joints since these joints will have the most stress.
Filed under: 1, Cornice Boards, General | 2 Comments »
Posted on February 22, 2008 by brevell
Posted on February 18, 2008 by brevell
Posted on February 18, 2008 by brevell
Posted on February 7, 2008 by brevell


When a shaped dust cover is required for a cornice board there are several alternatives. We could use bendable plywood (wiggle board) which is about 1/4″ thick and not suitable for today’s application. Another choice might be FirmaFlex, a bendable fibre board which can be ordered in six foot lengths and edge joined for longer pieces. If you are building your own cornice and cost of materials is not a big issue this could be a good choice but for the average workroom it would be a little too pricy. Next you could buy dimensional lumber such as a 1″ x 4″ board and cut hundreds of slots (kerfs) across the width of the board until it can be bent to the shape you want. Once again for the average workroom time is money so the time involved would rule this out. My choice of material for today is Homasote, a recycled newspaper material. They put the old newspapers in a huge vat, add water or other liquids and stir until the mixture becomes a mess of sludge. Then the sludge has most of the liquid removed, it is poured onto a flat surface and highly compressed to get the remaining liquids out. The finished product is cut into 4′ x 8′ sheets that are 1/2″ thick and similar to plywood although the cost is about twice as much. Homasote is easy to cut with a circular saw but very, very dusty so it is best to use a dust mask while cutting. For our arched top cornice we need 3 1/2″ returns so we cut strips of homasote 3″ wide. Since the cornice board will have a finished width of 111″ and the homasote comes in 96″ long sheets we will need to cut two strips and join them end to end with aluminum or steel edge joiners (sometimes called ‘dog ears’ because of their shape). Once the ends are joined we cut the strip about six inches longer than needed, stand it up on one edge, and lay the cutout plywood on top of the other edge. Then we start the process of stapling and bending, stapling and bending with the staples about three inches apart all along the top edge of the cornice. With a little extra beyond each end we can now cut down through the homasote at an angle to match where the curved top meets the straight top of the returns. You can either staple through the top board (homasote) into the top of the return board or staple through the top of the return board into the edge of the top board. The first way seems to be the most simple.
Filed under: Cornice Boards, General | Leave a comment »