Home>Discussions>EXTERIORS>Tell me how to build a triangle gable vent
9 posts / 0 new
Last post
guy48065
Tell me how to build a triangle gable vent

I've seen many homes older than 20 years with gable vents up in the peaks that appear to be made of wood with large shutter-like horizontal "bars", and look to be made on-site. My local builder's supply & big-box stores only have cheap looking plastic vents.

Back before everything went to plastic how were these built?

guy48065
Re: Tell me how to build a triangle gable vent

No house builders here? Maybe just young ones that prefer pre-fab?

A. Spruce
Re: Tell me how to build a triangle gable vent

How you build it will depend on your abilities, tools, and desired outcome. Is the triangle equilateral or more pyramid shape?

I would recommend box joints, this will make the angles easier to calculate and cut, and aid in assembly. A box joint is simply placing the end grain of one board against the side grain of the next.

Cutting the proper angles accurately will be your most difficult task, since saws only cut to 45*, and not the tighter necessities of a triangle.

Once you figure out the angle issues, then it will be slat placing and camber, the easiest way to do this equally and repeatably is to cut blocks to lay the slats on, Basically, you're going to have a side piece, between that you will place the slats (louvers ), then you'd alternate slat, block, slat, block, and so on until you got to the top.

guy48065
Re: Tell me how to build a triangle gable vent

Window screen on back? Should I just toenail it to the wall? I'm putting up cedar siding and will butt & caulk it to all trim.
Should I bridge the wall opening with studs even though it's a gable end?
Do people ever complain they attract hornets, wasps & bugs?

I feel they add a classy detail where the plastic ones are just functional. Just wondering if the little extra detail is worth the downside...

A. Spruce
Re: Tell me how to build a triangle gable vent
guy48065 wrote:

Window screen on back? Should I just toenail it to the wall? I'm putting up cedar siding and will butt & caulk it to all trim.
Should I bridge the wall opening with studs even though it's a gable end?
Do people ever complain they attract hornets, wasps & bugs?

I feel they add a classy detail where the plastic ones are just functional. Just wondering if the little extra detail is worth the downside...

Yes, you will want to install screen on the back, typically this is 1/4" hardware cloth, which is small enough for most pests and strong enough that critters can't break through it.

Not sure what your intentions are. If you build it like a typical gable vent, you can install it flush with your siding, then install trim over the face of it, or, you can incorporate the trim into the vent and attach the vent to the house via nailing through the trim.

If the vent fits between the studs, no need to install a bridge or header, unless you need a nailing backer.

Will they attract hornets/bugs, it's possible, yes. It is not uncommon for wasps to want to try to nest in them, but they're relatively easy to deal with. If you get a nest starting, you can use insecticide spray (though it may stain your cedar siding ), or just get up there and knock it down before they get a foothold, this method is best done at night when they're less active.

guy48065
Re: Tell me how to build a triangle gable vent

Thank you for the ideas :)

A. Spruce
Re: Tell me how to build a triangle gable vent

You are very welcome, please report back with your project progress :cool:

Sombreuil_mongrel
Re: Tell me how to build a triangle gable vent

I built a few of these for an old house (1820-ish) many years ago. First size and build the triangular "box" which must match the roof pitch exactly, and in a better quality example, will have the bottom sill pitched at a typical 6* angle to shed water. It should be sitting on a larger subsill that overhangs the siding so water drips clear. You can one-piece the box and make a wider, overhanging sill, but it does complicate the calculations and two-pieceing it lets you just think about the triangular box at this time.
Louver spacing is usually twice the thickness of the slat; 3/4" slat, 1 1/2" spacing. Between 30* to 45* slope to the slats is fine, lower slope , higher likelihood of rain blowing inside. Rip the slat angle on the edges of each louver so the outside presents a flush vertical face where it meets the box.
The compound angles (unless you're a trig wizard) are trial and error. I ended up buying a compound saw for that particular job, because I needed a saw that went to 62* miter angle for my design. I bought a bosch sliding compound saw, still have it.
Square louvers you can dado the slats in, but on a triangular one, you're going to be nailing and screwing the slats in place. If you dado these slats in you're building furniture, not millwork. You can play with the spacing so it's basically even-looking top to bottom without having a too-small non-functioning louver-ette at the top.
Generally it's better to plan on the casing overlap the slats by 1/2" to keep the ends out of weather.
Casey

guy48065
Re: Tell me how to build a triangle gable vent

Thanks for the additional details Casey. I like your comment about "furniture" vs. millwork :) I was actually considering sides made up of short parallelograms to space & angle the slats, attached to the triangle surrounding frame.

I think when I side the house I'll stop about 18" short of the peak & tack together a temporary frame to get the angles & size right, then build it in the shop. This is over logs so I'll need to remember to bring my chainsaw for the final install :eek:

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.