Do I want to caulk here on a window?
Hi everyone! My husband and I are building a tiny house… it’s our first construction project, and we’re trying to do things mostly right. I have a question about caulking around windows. We’re using vinyl windows with integrated nailing fins. We’re not doing window trim — the siding runs right up against the windows (which don’t have any kind of casing/channel/etc.). I’ve attached a diagram of the sill… my question is, should I have caulk where I’ve marked it?
It seems like caulk here would help avoid getting water behind the siding (it is set up as a rainscreen wall)… but it seems like I usually see warnings against having caulk at the sill…. but usually, the sill sticks out farther than the siding, which is not true in this case. My window set up seems a bit unique, and I can’t find any information about it. Thanks!!
Replies
You may want to consider an option like attached drawing. This gives you a non-rotting or non-rusting slopoing sill detail that drains water postitively away from the bottom of window. It also allows for:
1. better secondary seal of caulk
2. cavity to still fit cedar siding into to protect end grain.
3. opportunity to fine tune the fit of the sill off horizontal strapping by means of an offset screw driver.
PVC mills just like wood. If your not comfortable making enough material for all your windows, then consider hiring a millshop to make this profile for you. It shouldn't be too expensive.
Thanks, that's a good idea... however, we've already gotten as far as my drawing shows! We don't want to tear things open at this point.
erin
T&G siding running vertical or horizontal? And how are you detailing the J-channel around the rest of the window? Any wide overhang and a 1-story?
thanks
Running both ways, in different places... actually, some places will even be corrugated galvanized sheets instead of cedar (yeah, we have an interesting siding plan).
No J-channel around the rest of the window for the cedar -- probably J-channel around all 4 sides for the galvanized sections.
Not much of an overhang -- like an inch or two (metal roof). The entire house is on a trailer and needs to fit within 8.5' wide and 13.5' tall. Photos of the house here if it helps: https://www.facebook.com/spacecoasttinyhouse?ref=hl
Yowwwwww.
That is one fun undertaking, you have my admiration and encouragement!
I was curious of the plan and had hoped it was well thought out so there'd be no problems down the line. With different siding and different directions there's no way I'd offer an opinion. Being that it's a home on wheels there's then the dynamic of 60mph down the road, as I assume you plan to travel with it, no?
best of luck
Thanks anyway. I hope it's well thought out. I've done probably hundreds of hours of research into building science to choose the methods we use... it's just the final details that are a bit hard to research!
We'll probably travel with it at some point... though it may be more or less stationary for the first couple years. We'd avoid travelling in very windy/rainy conditions, just because pulling a 10,000 lb trailer isn't something we're super experienced with.
In the future....
That window buck should have come out flush with the face of the furring. In this way, the windows would have stood pround of the siding by 1/2" or so and allowed the window integral drip edge to do it's job. To depend on caulking as a first layer of waterproofing is to guarantee future leaks.
This looks a lot like what happens when the vinyl siding contractors install new siding over existing. The J moulding ends up in front of the windows. Not an optimum detail.
In response to your question, you must caulk this joint...you cannot allow water to pour in behind the siding. Wind pressure on this wall will force any water coming to rest on this intersection into the joint. It's the only thing keeping water out of the wall...
Thanks for the answer. Yeah, when I was planning things out, I thought about bringing the buck farther out. But, I thought this would make the flashing difficult, because it would have a bend in it. I guess that would have been less of an issue than what I did though!
Anyway, I will caulk the joint; you've confirmed what I was thinking. I believe it won't be a big deal if a little bit of water gets behind the siding, since I have taped tyvek as a barrier, and I've back primed the siding... the caulk will help keep out the majority anyway.
Don't skimp on the cost of the caulk...
Get a good quality polyeurthene caulk to do the work. Don't scrimp on the cost and get a $2 tube of acrylic...