Diy upvc windows part 2 how to install upvc windows, lets review for a moment in part one we discussed preparing the timber sash window openings for diy upvc window installation if you have not read part one I suggest you go back and read it before you consider diy upvc windows installation, there is more to it than just taking out the windows. OK we have our openings for our diy Upvc windows or a (double hung windows) we have taken out the old timber sash, insulated the weight pockets checked for any gaps, or cracks and caulked them. We also made sure the out side casings were OK and nailed on tight. Lets assume for a moment that our diy upvc windows openings are square, level and plumb, when you measure these opening for new diy upvc windows you want to wind up with the diy Upvc windows being about one half to three quarters of an inch smaller on the width than the window opening and a half to three quarters of an inch smaller than the opening on the height. There is a lot more to consider about measuring timber sash window openings for a diy upvc windows replacement, there will be a separate article about that in the near future.
“Diy upvc windows Tip” The first thing you want to do is to try a dry fit, put the window in the opening and make sure everything looks and feels OK. Check to make sure that your diy upvc windows sit properly in the openings , check to make sure its out between the new diy upvc windows and the timber sash all the way and up against the outside stops. Check the openings, if everything thing looks OK then take it out. Standard upvc sash windows (or double hung windows )comes with a expandable header on top of the window which helps you take up any space between your new diy upvc windows and the timber sash openings, you should install the diy upvc windows with out it if you can, having an expander on top of the diy upvc windows changes the width at the top and forces you to alter the interior trim at the top to get a good fit when you put the trim back on later. Just check the space on top first to make sure it covers on the outside and that the interior head stop will cover when you put it back later. If your window opening is out of square or the space between the new diy upvc windows and the opening at the top is to big use the expander. When your getting your diy upvc windows ready to go into the openings put a piece of insulation under the header it helps fill the void and helps keep the expander all the way up to the top of the opening.
If your new diy upvc windows come with a shipping strap around the middle leave it on till you get them settled in the openings
Its very easy to dislocate the diy upvc sashes when the diy upvc windows are not installed make sure the upvc sash windows are closed and locked before you start handling them and don’t pull on the sides or roll it on its corners, again its very flimsy until their installed. Lets talk about caulking for a moment, There is a lot of caulking to choose from and most people talk about silicone as the best choice, and it is good as a sealant but is not that great as an adhesive sealant. I have seen many diy upvc windows 5 or 6 years after installation only to see the silicone seal between the diy upvc windows and the exterior stops separated. There are a lot of stress on that joint with expansion and contraction. If you can get something like a Terpolymer rubber adhesive sealant or a urethane caulking that would be fine. When your shopping for caulking Look at the labels for words like adhesive sealant, Dap 3.0 or solar seal# 900 are both very good. OK we are going to caulk the opening before we put the diy upvc windows in the openings, a lot of people don’t do this and its a big mistake. Its a great place to create a bond between the diy upvc windows master frame and the out side stop You don’t want to go through the all the work of putting nice new diy upvc windows in only to find in the middle of winter you have a big draft. Inspect the out side stop make sure its totally dust free and then put a bead of caulking all the way around both sides and the top in one continuous bead about as thick as a pencil. Next run a bead across the bottom of the window sill up against the window stool about a 1/4” to about 3/8” deep and then another on the window sill where the sill expander of the diy upvc windows will sit just inside the back stop from left to right, Now run a bead across the top where the head expander will push up to. Try to be neat, caulking is an art and it can be messy if you haven’t done it before. Make sure all your caulking is in place and there are no gaps in the bead, we want to create an air tight gasket. Pick your diy upvc windows up by the sides and carefully set it on the bottom on the window stool check the spacing from left to right and then lower the bottom of the diy upvc windows into the openings then slowly push the new diy upvc windows out to the out side stops firmly till its out all the way out and the caulking squeezes out. At this point check the gap around the perimeter again to make sure its even, then holding the diy upvc windows in place take a long skinny straight edge screwdriver or some long nails and put it up against the diy upvc windows frame and hammer it into the wood frame to hold your new diy upvc windows in place. Do this on both sides of the diy upvc windows up at the top, right near the head expander. Make sure the upvc window is seated all the way down in the opening, some times it gets tight between the window stool and the out side stop. OK lets take a quick look at how our new diy upvc windows are sitting in the timber sash openings, unlock the the window and slowly open the bottom sash about an 1/8” inch and pull the top sash down about the same. Check the crack of light from left to right on both sashes, now look at the margins between the wool pile of the sash and the master frame of the diy upvc windows we are looking for consistency here.
Plumb level and square are always the rule when installing diy upvc windows
But by opening the sashes we can see how the sashes are behaving in relation to the the diy upvc windows frame. If the crack of light is not the same from left to right we can tell something is off. Why don’t you just use a level and make sure it’s all plumb and square? Well you can, and you should, but at the end of the day we want the new diy upvc windows centered as best as possible in the openings, and we want the sashes of the new diy upvc windows square to the master frame and them selves. In this case the spirit of the law is more important than the letter of the law within reason. If your whole house has settled 1/2” out of level and you now try to install your new window level you may create more problems than you solve. First of all visually you will draw attention that something is out of whack but more importantly if you have to shim the diy upvc windows up on one side your creating a weak spot that I will talk about later. Again check the crack of light on both upvc sash, check the space between the wool pile of the sashes and the window master frame and the space around the perimeter and if all is well then shim the sides with just enough pressure to hold them in place be very precise to much pressure and you will have problems opening and closing them forever, not enough and you will get air infiltration make sure the pressure is the same front to back. Usually shimming the middle of both sides is enough, after you finish check the gap between the sash and the upvc master frame where the wool pile is from top to bottom on both sides. Then again recheck the crack of light of both upvc sash if all is well close and lock the sash, run your fingers across the meeting rails where both upvc sashes come together make sure its consistent if it’s OK cut the shipping strap off be careful it might have some caulking on it. Open the bottom sash and install the screws into the diy upvc windows master frame their should be a total of four screws two at the bottom and two at the top. The ones at the bottom are in the corner usually located under a movable cover, when you put the screws in make sure you just make contact with the diy upvc windows master frame and give it one or two turns, be very careful with this step because you can easily distort the master frame especially if your using a cordless drill. Then put the screws in the top and check the crack of light and the rest of the margins between the wool pile if you over tighten the screws you will see it now, if so back the screws off a little and then check it again OK Time to insulate, if your using fiberglass insulation its easier if you cut in into strips with a sharp utility knife, lay a piece of plywood and then lay a straight edge of some type on top and run your knife along side to cut the strips. Using a putty knife work the insulation between the window and the timber sash opening. Once again you have to be very careful not to jamb the insulation so much that you distort the frame and put undue pressure on the upvc sashes. After you have insulated both sides and the top (if you didn’t use the header expander), open and close both upvc sashes to make sure they work properly. Now if the space around the window is less than 3/8” of an inch you should caulk both sides and across the header of the expander this give’s you another layer of defense against air infiltration and it glues the diy upvc windows frame to the timber sash opening. OK time to put the interior trim back on, most of the time the head stop is not the same width as the side stops if this is the case than you need to break out the table saw. But first put one of the side stops back temporarily to see where it falls in relation to the interior casing, take that into consideration when you determining the width to cut the header usually you can cut the header the same width as the sides. OK another bead of caulking goes under the back stop and the header, make sure you caulk the seam of the weight pocket door while your at it. Time to put the interior stops back on, start with the header, a couple of four penny finish nails will do, when you put the side stops back on put one end in first and then put a little bow in it the middle of the back stop to take the pressure off and sneak the other end in place don’t use a hammer on it or you will split or break the ends of the stop. And finally how about a little more caulking( yup that’s a lot of caulking) between the diy upvc windows and the back stop all the way around the window and then one more time at the joint between the back stop and the interior casing. Now we would only caulk here if the interior finish is painted This is an area that you would use a latex type caulking some thing with a little body to it like phenoseal its a vinyl adhesive caulking it works well inside and is paint able. If you have a natural finish with polyurethane then you can use a clear silicone or dap 3.0 clear. And finally we need to caulk around the perimeter of the exterior between the diy upvc windows and the exterior stop and then across the sill. As you can see we used a lot of caulking around the new diy upvc windows in some cases about 4-6 times as I said earlier every area you caulk gives you another layer of protection against air infiltration and gives structural support to the diy upvc windows master frame buy gluing it to the timber sash opening Remember most of that caulking is hidden and it can make or break your installation, five years down the road those diy upvc windows you installed will be as air tight as the day you installed them. Ok give yourself a pat on the back your done, crack open a cold one and take the rest of the day off! But before you go, a couple of notes, during the installation I mentioned not wanting to shim the upvc windows if we didn’t have to there is a reason for this. When the new window sits in the timber sash window opening, the sill is typically pitched 15 or 20 degrees and the front of your diy upvc windows are kinda floating in air with out much support. Upvc sash window manufactures address this area differently some give you an L shaped piece that you fasten to the window sill and set your diy upvc windows on top of it, some give you a piece that attaches to the bottom of the diy upvc windows frame, and then there are some that supply you with a upvc leg that snaps on to the face of the diy upvc windows after installation. That type is probably the best because you can shim the diy upvc windows where it needs to be and insulate underneath the window and then put the extension leg on last. The other types don’t really work well because if you shim the window and then knock the expandable piece down, the front edge of diy upvc windows have no support. And if you put the shim under the expandable piece you have a gap to caulk, still not ideal .In extreme situations you could cut a piece of wood filler tailored to fill the gap, and to provide support to the front edge of the diy upvc windows frame its the kind of flaw that would show up a few years down the road. What ever way you choose make sure you get insulation under the diy upvc windows frame at some point during installation.