These days a lot of homeowners are replacing their old windows with vinyl windows using the retrofit style of window frame. This is particularly true in the west, and specifically, in California. The number one arguement that I have heard against using the retrofit method, is that it is susceptible to water leaks. Well, that’s true if you don’t do it properly. But, if you do a complete tearout of your old window down to the studs, you’re going to have water leak issues there as well if you don’t install the new window properly. So I think that arguement is, well, all wet. So, let me tell you the best way to install your retrofit windows that will ensure that water cannot get in.

There is an old song that goes, "It never rains in California, but girl don’t they warn ya, it pours, man it pours". For those of you in California, you know how true this is. While California doesn’t get a lot of annual rainfall, when it does rain, it can come down in buckets due to the close proximity to the ocean. So, you want to be sure that your windows are well sealed.

If you are installing retrofit frames against a stucco house, you want to put a thick bead of sealant right on the outside face of the old window frame, all the way around. Latex caulk should work fine, but if you want to spend a little more to get the best sealant available, use 100% silicone. Depending on the number of windows you will be doing, this extra cost can add up.

You pay approximately $1 for a tube of acrylic latex caulk, and $4 or more for a tube of 100% silicone. You are going to use 1-3 tubes per window, depending on the size. So you can see how it could add up. Here is a trick that I used to do to save a little money; The most vulnerable part of your installation is the top of the window, because gravity will have the water running down from the roof to the ground. It’s not likely that water is going to find it’s way through the sides or bottom.

So, I used to carry two caulking guns, and load one with the silicone, and the other with the acrylic caulk. I would run the silicone accross the top of the old frame, and caulk the sides and bottom. Then, put your new window into the opening and have a helper hold it firmly in place while you plumb and level it, then screw it into place.

After you have the window completely installed, your final step should be to caulk where the retrofit lip meets the stucco. Here again, I used to use white silicone on the top, and caulk on the sides and bottom. You now have a double barrier against water infiltration. After about a week, check the sealant around each window for signs of cracking. Because stucco is usually uneven, there could have been gaps that were larger in some areas than in others.

If you don’t force the caulk into the gap to completely fill it, the caulk can sag before drying, causing a crack to form. Simply recaulk over any cracks that you see. You can check the silicone on top as well, but because silicone dries like a rubber substance, you shouldn’t see any cracks there. OK, what if the replacement windows are going between wood trim surrounding the opening? If you are using the retrofit lip, and trimming it to fit between the wood, then you still apply the heavy bead to the old frame before installing the window. But, instead of sealing where the retrofit lip meets the stucco, you seal where it meets the wood. Then, you want to be sure to seal above the window, where the top piece of wood meets the stucco. Again, use silicone up there. Now, no water can run down the stucco wall and get under the top piece of wood.

Sometimes, though, you might decide not to use a retrofit style frame between the wood, choosing a block replacement frame instead. If you choose to do it this way, you have to add trim to the outside. You still want to apply the sealant to the old frame, then apply your trim so it contacts the new window as well as the sealant on the old frame. If you follow these procedures, you won’t have to worry about any water penetrating into your home, I don’t care how hard it pours!

John Rocco has been installing replacement windows since 1978. To learn more, visit How To Install Windows

3.1. From scrap ply or board and 2x1 or similar make a clamping fixture (see photo) that can clamp the inner frame to the cabin side via vertical and horizontal legs cramped to the cabin locker below the window. Shape the ply or board to give access to all the fixings. To ease handling, attach the board to the vertical with string through the contact point; bolt the two legs together – this ensures that the fixture can be positioned with one hand. Make the fixture before removing the first frame.

4. The original windows were made of an aluminium alloy, secured with rivets. Later boats have bronze windows, secured by a variety of means. Mark the top of the inner and outer frames before removing them. Do the complete job on one side at a time – allow two and a half to three hours for each side.

5. Make sure you can work comfortably, as well as safely, inside and particularly outside the boat; you will be spending some time doing careful work that needs a steady base.

6. To remove the old windows, drill out the rivets. Do this from the outside using a drill bit of about 6mm. The aim is to remove the flange so that the remainder can be gently punched through & out. If the rivets are heavily corroded into the windows, they may need to be completely drilled out. In that event, use a drill bit which is a clearance diameter for your fixings.

7. The old alloy frames become brittle with age so very carefully lever the window frame off by hand moving along the window in short stages. If you simply pull one end off the window and keep pulling, the lever arm will become too great and the frame will snap. The only option then left is to fit new, bronze windows. Very nice but very expensive; available from Churchouse Boats.

8. Clean off all the old sealants from inside and outside the cabin and from both inner and outer frames. Allow up to two hours for cleaning. You must get all traces of old sealant off and degrease the frames and cabin side before proceeding further.

10. Work on the frames on a thick soft pad; the frames are slightly curved and might break under pressure on a flat surface. Cleaning the frames will leave sharp edges, break them with a file; drill through the frame holes to clear them out and break the edges of the fixing holes with a countersink.

11. Refitting the windows is a two person activity. One inside the cabin – one outside. Your inside helper needs to give you about 15 minutes of their time. You will be applying sealer only to the cabin and to the parts already on the cabin. The inner frame, acrylic and outer frame will have no sealer on them when you fit them, one at a time.

12. Make a dry run following the instructions below to make sure all parts fit with the necessary clearance and that all fixings pass through their holes and can be tightened. Particularly check that the acrylic is clear of all the fixings. Ease the edges locally, if required. This is easily done with coarse abrasive paper or fine file. If the fixings clip the edge of the acrylic as they are installed & tightened, the glazing will crack.

13. Apply a continuous bead of sealer to the inside of the cabin where the inner frame will sit. Using four bolts as a guide offer up the inner frame and clamp it in place with your fixture. Check that remaining fixings will pass through their holes.

14. Move outside and fill the gap between the inner frame and the cabin opening with sealer. Then apply a bead of sealer to the cabin where the acrylic will sit. Remove the temporary protection film from the inside face of the acrylic and lay the acrylic in place. It will stay put because of the angle of the cabin side and the tackiness of the sealant. Remove the outer protection film.

15. Apply continuous beads of sealer to the outside of the cabin where the outer frame will sit, around each fixing hole and on the mating face of the acrylic. Fit the outer frame and fixings, in diagonal opposite pairs and finger tighten. Remove the four guide fixings and replace from the outside.

16. When all fixings are in place, finally tweak them up. They need to be tight enough to squeeze the silicon and hold all secure.

17. Once all is set and cured, very carefully cut off any surplus silicon that has oozed out. A scalpel-sharp knife is a good tool, carefully used. Whatever other method you employ, do not, under any circumstances, use acetone to remove surpluses. It will instantly cause your new acrylic to turn opaque.