Hi, I am Joe Cochran from NorthlineExpress.com. Today we are going to go over step by step on how to install DuraPlus Chimney System in a flat ceiling supported through the roof installation.
How to install DuraPlus Chimney System
Your first step is going to be to find the center point between the trusses and mark it so you can install your round ceiling support. The first measurement we are going to need to take is from the back wall to the center of the flue opening. In this case we are sitting at exactly 24” to the center. On the ceiling you will want to measure 24” from the wall, make a small mark and that is where you will start with your plumb bob. Place the plumb bob in the center of the flue opening and line the string up with the mark on the ceiling. Make a mark where the string meets the ceiling and this will be the center of your opening. Now use a stud finder to assure that the mark is between two joists. Then you will need to make a small hole in the ceiling where your mark is leaving the drill bit in place (an old metal coat hanger works well for this) so that you can go in the attic to make sure the placement of the opening is going to be appropriate in relation to the joist opening.
Next step is to go into the attic space and locate the area where you made the hole. Peel back any insulation that is in the area. Now you will want to measure to see how far off center you may be from each joist. If you are close to center, take your ceiling support, turn it upside down, center the ceiling support box over the hole, and mark around the box for your cut. Start your cut, leaving a small area uncut so the piece does not fall through onto the stove in the room below. You will need to take measurements of the space surrounding the opening before you leave the attic to go down into the room where you will be finishing the cut. This is so you can cut the pieces of wood that will frame in the ceiling support box.
Once you are back in the room of the install you will finish the cut of the opening. Next you will want to cut your pieces of lumber to make the framing for the ceiling support box and then head back to the attic. It is time now to build the framework to attach the ceiling support box to. The frame is what is going to support the weight of your chimney stack so you will want to make sure that it is secured in there well. Once the frame is secure you will then place the support box into the opening. When installing this box the keys to keep in mind here is that the bottom of the round ceiling support has to extend into the room 3” just to get your clearance to combustibles. Then you will secure it to the frame with 3 – 1 ½” screws or nails. We recommend using screws because they are easier to put in while in the attic and there is no chance of banging up the support box while trying to hammer nails in. It is important to get the support box level when installing it. Secure one side and use a level to ensure that the support box is real nice and level before securing the other sides in.
Before leaving the attic to go install your trim ring, use you plumb bob to mark the center of the roof opening just as we did to mark our ceiling opening. Once you have made the mark you can drill through leaving your drill bit in the hole to make it easier to locate the hole when you are on the roof. Now you can install your trim ring and head outside to the roof.
When up on the roof locate the drill bit that you left in the hole. When you are installing DuraPlus you need 2” clearance to combustibles on all sides of the pipe. The inner diameter of the DuraPlus for our installation is 6” so the outside diameter is going to be 10”. To ensure that we meet the 2” minimum clearance our opening has to be at least 14” in diameter. What you have to keep in mind is because your roof is not flat and you have a pitch to it, if we were to just measure 7” above and below the drill bit we would end up a little too close on the top and a larger gap on the bottom. So what we will need to do is shift our measurements a bit so that there is a larger opening on the top and less on the bottom. For the width you can mark 7” to each side of the drill bit. Now just connect your marks giving you a guide for you opening.
To cut the opening we are going to use a special bit that is going to allow us to cut an actual hole in the roof so that we can fit the blade of our reciprocating saw through to cut this opening out. Now do not worry if you get it cut out and put the pipe in to measure it and then you see that it is a little too close and you will need to trim more off the top or the bottom to accommodate the 2” clearance. It is always preferred that you have to trim a little extra than have a hole that is too big. To check you opening size, insert the first section of DuraPlus Chimney pipe into the opening with the female end down. The DuraPlus pipe has a twist lock connection that will give it a secure fit into the support box. Our opening needs to be trimmed more at the bottom.
Once you have your opening to the correct size for your pipe this is the time when you will go back into the attic to install your attic insulation shield. The Attic Insulation Shield needs 15” of height from the frame to the roof. For our installation we will not be able to use the attic insulation shield as our attic height is too short to allow it to fit. So what we will have to do is build a chaise closing in the pipe to protect it from coming into contact with any debris or insulation in the attic space. We will be using ¼” particle board to create the chaise. It does not matter what type of materials you use to build the chaise as they will be outside of the 2” clearance to combustibles for the pipe. Once you have installed your Attic Insulation Shield or built the chaise, you are now ready to return to the roof and complete the installation from there.
It is now time to install the roof flashing. To do that the first thing that we need to do is get some of the shingles lifted away from the roof at the top of the opening to allow the top part of the flashing to slip under them. Use a pry bar to carefully peel up the shingle to break the tar seal. Try not to tear the shingle the best you can. Once you have it peeled up you will see that there is a strip of tar and there will be nails in the strip as well. The nails are what are holding the shingles down so you will need to pop the nails out of the strip of shingles that you just lifted. Now that the shingles are popped and the nails are out it is time to slide the roof flashing up under the shingles. The steepest end of the flashing goes to the bottom of the opening. Before you seal the flashing down, test fit the pipe to ensure that the flashing is in the correct spot centered over the opening. The next step will be to trim away any excess on the shingle above the hole so that there is a nice fit. Then up underneath of the shingles is where you will nail the flashing to the roof in a few spots. The portion of the flashing that is not covered by the shingles will be sealed and secured with a bead of silicone. It is recommended that you nail down the sections that are covered by the shingles, if you do put nails in where there is no coverage from the shingles you should cover those nail heads with silicone to prevent any water from getting into the roof. Also put a generous amount of silicone around the edge of the flashing sealing any openings between the flashing and the shingles. The first section of pipe may be installed once the flashing is completed.
Now that we have the flashing and the pipe installed we can install the Storm Collar. Start by putting a bead of silicone around the area where the storm collar is going to hit your flashing. We are going to use a RTV 500 degree high temp silicone. When starting your bead apply it just a bit higher than the top of the flashing this allows a good seal to be made when pulling the Storm Collar down over the flashing. Place the storm collar over the pipe and insert the tab into the first slot, then back up through the second slot, and then bend the tab back over the slots to secure it into place. Now slide the storm collar down setting it into that initial bead of silicone. Finish with one more bead all the way around the top and that will seal it off. I also recommend that you run a bead of silicone down the seam of the storm collar just to seal it up the best you can. This is going to stop any rain from dripping down the pipe and getting into the home.
To finish of the installation of the DuraPlus Chimney System the last step is installing the chimney cap. This is real simple because DuraPlus has the twist lock connection. Just place the cap on the top of the pipe, push down, very carefully turn it, and lock it down into place. If you are installing a spark arrestor in the cap you would simply remove the four screws install the mesh spark guard and the reinsert the 4 screws. We do recommend installing a spark guard as this will keep any loose ember from exiting and also keeps any debris or small animals from getting into the chimney system.
I hope you have found this information to be helpful. Please make sure that you check out our Chimney Pipe Learning Center to find even more how to videos and articles on chimney pipe.