Plexiglass question for house project

[efiske]

Hello everyone,

I'm working on a project at my house and looking to use plexiglass or similar polycarbonate. I am using the materials to cover up two window wells to the basement windows. The 2 openings measure approximately 49"x32" and 49"x34". The plexiglass will be affixed with clear caulk to treated lumber on 3 sides of the opening with approximately 1.5" lip, and butted up against the brick facade of the house on the 4th side. There is a slight slope up to the house for rain water to run off(approximately 8 degree slope). One additional consideration, currently the window wells are being covered by half inch sheets of plywood. I have 2 large dogs(100-120 pounds each) that have taken to laying on top of the plywood. Because of this I am wondering if there is a material or thickness you could recommend that could withstand the weight of a large dog standing on it. Hoping they will stop this habit once the plywood is removed and clear plexiglass is installed, but trying to prepare to avoid and potential hazards.

Thanks for the help here!

 

[3DDave]

Plexiglass is acrylic and tends to brittle fracture. Polycarbonate is much tougher. There is fiberglass reinforced walkway material such as is shown here:

https://nationalgrating.com/fiberglass-grating-walkways/

that you could put over or under the plastic to take the weight of the dogs. It may be worthwhile to make an elevated platform of plywood that is a more attractive location for the dogs to hang out and transplant them from the window.

Note that a regular drill bit will shatter Plexiglass; there are special designed bits for this that don't cost much. I mention this because I am not confident about the caulk. Also, the clear caulk is unlikely to stay clear as UV will destroy it and turn it white. So if later on you decide to try screws, recall to get the right bit. Polycarbonate is a bit better. For example. when cutting Plexiglass there is a carving tool that removes a trench of material. With acrylic/Plexiglass scoring about half-way is good enough to be able to snap it like glass. With polycarbonate one pretty much needs to cut the entire thickness. A handheld jig saw is not a good choice for either material as the plastic will melt and foul the blade; worse, the hot shavings will cool and rebond in the cut behind the blade and make unmake the cut. How unhandy.

 

[efiske]

Thank you for the recommendation 3DDave! I don't think I will go the route of the reinforced walkway, as one of the main goals is to get sunlight into the basement, and it looks like those fiberglass walkways would block out quite a bit of light. I have considered possibly putting 1 or 2 steel rods underneath to help support and weight that gets put on top; not super aesthetically pleasing but certainly better than broken plastic and an injured dog.
Interesting point about the UV light discoloring the caulk, I also read yesterday that polycarbonate(made from oil) may not be a good choice because it could also yellow in the sun, where as acrylic(made from natural gas) would not run that risk. I am an extreme novice here and just barely scratching the surface learning about all of the various types of plastics and potential applications, so any and all recommendations or information is greatly appreciated.
I may take your advice about screwing the piece down to make sure it is secure, but I also need it to be weather tight, so perhaps a beam of caulk underneath would still be necessary.

Thanks again for your insight!

 

[itsmoked]

It's not completely clear to me what you're doing but when covering another window with something you run the risk of having water and condensation piling up between the two. You will end up with mold and slime between them and any involved wood rotting.

Recommend another method of some sort and an active plan to move the dogs.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MikeHalloran]

Our new house in upstate NY has two small window wells, and one large one, all covered to nominally protect routes of egress.

The covers are all polycarbonate, and stocked in appropriate sizes at the local lumberyards.

The smaller ones are retained by screws driven into the sheathing through the siding, effectively hinged at the top so a very thin person could actually push them up and climb out. The PC is tough, rather thin, and reinforced by ribs pressed into the material.

The large cover has ribs pressed into the PC, but they are not real deep, or real stiff, and sagged enough from rainwater to allow the water in.

That cover now has a crowned 2x4 spanning its underside, retained by short pieces of wood on top, each having two screws drilled through wood and cover, in aggregate reinforcing the cover well enough to stop it from leaking, or from deforming much under a foot of heavy snow.




Mike Halloran
Corinth, NY, USA