Modern Window Detail – The CHouse Modern

June 16, 2014 — 39 Comments

It’s been 2 1/2 months since I last updated you on the CHouse Modern project and a lot has happened. The last time I showed you the house, it was about 15% complete with the structurally insulated panels (SIPs) going in. Since that time, the rest of the SIPs were put in place, the roof has gone on, interior electrical, HVAC and plumbing rough has been completed. It sounds like I’ve been sleeping on the job but the truth is that this house is diagrammatically very simple and there hasn’t been a whole lot to show you just yet. In addition, there was some delay when all the roof trusses were fabricated incorrectly. We had shop drawings but somehow what was in the drawings didn’t show up on the job site. Getting that issue resolved wasn’t difficult at all, it just ate up time. Other than that, this project has been moving along extremely well.

We have been attending regularly scheduled job site meetings that occur once a week. More times than not, I simply take record photos and we do a “look ahead” with the contractor to make sure that there aren’t any questions looming that the team isn’t prepared to answer. The last site visit was to do an inspection on the installed aluminum window “boxes” that are a major design feature on this house.

CHouse Modern Model Pool Aerial

If you look at the project model we made during the design phase of the project (this model was built Summer 2013), if you look at the windows, you can see that there is a basswood surround enclosing all the windows. The doors have a different metal treatment that will happen later but for now, I think I’ll focus on the windows.

We have a Marvin door and window package on this house – the Wood-Ultrex line – which is a fiberglass clad wood window. It’s a very clean-looking window, very good thermal performance and an overall excellent product for the price. The exterior geometry on this house is somewhat fixed and all the penetrations in the exterior wall needed a little extra attention so that their appearance was commensurate with the aesthetic role they play. We decided that all the windows would receive an aluminum surround that projected out from the finish face of the wall to heighten the perception of the depth of the windows placement within the wall. It is also our expectation that the shadow lines these projected boxes will add to the facade will help break down the scale of the 2-story high walls.

Aluminum window box detail


This is one of the details we created – although this was really the drawing that would start the conversation with the metal fabricator on what should “actually” be done. Turns out we were pretty spot on with how we drew this detail up – pretty simple looking and you would never know that we spent more time that I would care to admit discussing how this detail should be executed. Basically it’s an aluminum rectangle that’s an 1/8″ thick (11 gauge) … it gets screwed to the exterior wall framing and the window gets set inside it. We had to discuss expansion and contraction of the metal, how to properly seal and flash the assembly – there were meetings with the metal fabricator, etc.

CHouse Modern Aluminum Window Boxes lying in wait

The cost for these aluminum boxes averaged about $523 per unit which considering the design impact they will have on the project is a bargain. We did have a fabrication issue in the beginning that we had to contend with – the welds that appear at the corners. They were rather small welds but the attention given to the welds during the grinding process left a little to be desired as a finished product.

CHouse Modern aluminum window boxes bad craftsmanship

Here is a close up look at the edges that were welded and then grinded – not very pretty is it? We called for a mill finish on the aluminum because we wanted to hold the reflectivity down on these boxes but even then, these grinded edges would reflect light a lot differently then the rest of the boxes and it would be easy to see from a distance. The solution was to sand the entire surface of the aluminum boxes to bring the finish to a matte finish.

It worked wonderfully which hopefully you’ll see for yourself in the next few pictures.

CHouse Aluminum window surounds at pool court

This is the rear courtyard of the project – all of these areas look out over the hill and at the future pool. (look at the first model picture in this post to see the “finished” area.) The lower areas are mostly doors and they will receive metal cladding – it’s all the windows, mostly on the 2nd level – that have the aluminum box treatment. The exterior wall finish is iron spot brick on the first floor and then stucco on the 2nd level. That transition in materials happens at the aluminum brake metal band that you can see in the picture above.

CHouse Aluminum Window Boxes detail view

You can get a pretty good sense for how the aluminum boxes will project out from the walls and increase the perception of the depth the windows are set.

CHouse Aluminum Window Boxes detail view

Here’s a close up look at the box installation into what will eventually be a brick clad wall – there is still a bit of weather-proofing that has to occur.

CHouse Aluminum Window Boxes detail view

CHouse Modern Model motor court 02

Here is a reminder of what the arrival courtyard will be … maybe you’ll notice in the following construction photos that a second level was added above the garage after this model was built. Added to the programming was the addition of a playroom and another bedroom/bathroom.

CHouse Main Entry View

I am standing on the neighbors lot looking across at what will be the entry motor court. The concrete retaining wall that’s between me and the house will be backfilled and all but a few inches will be visible.

CHouse looking at 2nd story

I am standing in the playroom on the second floor looking back towards the spot where I was standing in the last photo.

CHouse Aluminum window surrounds on the 2nd floor

Another look at the windows that will be set in a stucco wall.

CHouse Modern aluminum boxes interior installation view

Here is a look at an interior corner – you can see the rough opening framing, there is 1/4″ allowed for shim space (which has now been filled with expanded foam, the edge of the aluminum box – another 1/4″ for shim space – and then the fiberglass clad wood window. These windows will not have trim around them on the inside face, the gypsum board will be turned into the window, nice and clean.

CHouse Aluminum window surrounds on the 2nd floor

This is an exciting house for use for many reasons, we think it’s a very clean design, interesting material palette, it has new (to us) construction technology that was a first for us, and an adventurous owner (who I don’t think I’ve ever seen without a smile on her face … even when the trusses showed up the wrong size …). We are tracking the process of this house because while not inexpensive, this is a house on a tight budget and is projected to come in at less than $150 per square foot.

Hopefully you light the aluminum boxes as much as I do, I think they are turning out quite nice – just like we thought they would.


Bob AIA signature


Print Friendly

even better stuff from Life of an Architect

  • Slick detail but oh my….now that is a massive thermal bridge! Regardless of the climate, be it hot or cold, the thermal performance of the SIP’s and window frames will be bypassed by what is essentially a frying pan extending right into every rough opening. I appreciate the architectural nature of the finished look but in the future I recommend bending the aluminium to create an “L” where it meets the sheathing rather than running the aluminium right into the rough opening. This would allow the aluminium frame to be nailed through the sheathing and into the 2x framing which would eliminate the thermal bridge. If that same detail were in a cold climate the cold aluminium would bridge through to the interior and condensation would be 100% guaranteed to form leading to mold, rot and an ugly lawsuit. In a warm climate the aluminium would add considerable internal heat gains which would add to your clients cooling bills each and every month. I was honestly just searching for modern sill details when I came across this and had to say something as a thermal bridge which breaks the basic rules of building science is certainly not “subjective” in my experience.

  • nedmorlef

    As a unemployed window expert i would suggest you lose the expanding foam. That stuff will put undue pressure on glass and push frames out of square.

    • maxthomas

      Good call. I couldn’t agree with you more. It doesn’t take much to over do it with the expanding foam and by then the damage is done creating a lot of corrective (time consuming) rework.

  • Pingback: Can I use Structural Insulated Panels in a Hot Climate? - Quora()

  • Jared Reed

    Bob, in theory the detail is very elegant, but I can’t help feeling that it’s also not overly practical. These projections seem like perfect covered porches for birds to hang out on and leave unsightly deposits, etc…

    • maybe if this project were located in a more urban environment, but there are hundreds of trees on this lot and I can’t ever think of an instance where unwanted bird perches were an issue on one of our residential projects.

      If this proves to be the wrong assumption, I’ll come back here and admit it, I’ll chalk it up as a lesson learned.

    • Bamgbopa Folarin

      i think i quite agree too, the projections are quite a little too much

  • Tina Ryan

    We are bonding aluminum posts by soldering (not welding). Gives clean, seamless strong bond and mill finish is maintained.

    • that’s an interesting thought – how thick is the aluminum you are using? Did you do a cost comparison between the two fabrication methods?

      • Tina Ryan

        My fabricator had a paroxysm when I told him about my suggestion to solder joints in this application. He read the blog and I’ll relate his response”
        The job looks like it was TIG welded and this will always leave beads in the joint that need to be grinded to

  • Stephanie

    Thank you for sharing – I’ve seen this detail incorporated on buildings here and there, and have always wondered what the details looked like. Terrific example of a simple material and move (excluding the hours of detail debate) to create a big impact – nice!

  • Scotty Amen

    Please don’t be offended, but personally I’m not a fan of this window style. It stirs up vague associations with slums / Brazilian favelas, or the type of house we found Bin Laden hiding in. I would not want these. Again, please do not be offended, this is just the association my brain makes. They look like they come from a poverty-ridden hostel in Naples or something, or a scene from war-torn Kabul. I love your site but these windows are not appealing to me personally. Hope I didn’t tear you down too much on this. You are a great architect but these window treatments do not work for me personally. Sorry to be the only dissenter.

    • so if I understand, you don’t like this. Maybe the fact that it isn’t in a slum or that the surrounding walls aren’t riddled with bullet holes, or maybe that there aren’t homeless people lingering about would help disassociate this window from the places you mentioned (fingers crossed).

      • Scotty Amen

        🙂 Yeah I was hoping you wouldn’t get defensive …

  • RG126

    Is there not a cold bridging issue with this detail?

    • yes … although “issue” is subjective

  • Robert Moore

    I’d like to see the head detail to see how the rain is being handled.

    • I bet – I’ll see what I can get together for you

  • lardavis1951

    Wondering how the sound of precipitation will be interacting with that aluminum surround. Perhaps you’ve already given it a test? I used to be playing cymbals in marching band, but I’m asking more because when the condo got new windows and siding I hear every raindrop – esp. when wind-driven.

    • It was raining – pretty hard – the day before we got there and the owner didn’t mention it. There was light rain falling and there wasn’t any perceptible noise specifically from the aluminum surrounds. Maybe it was due to the thickness of the aluminum as well as the insulating foam that encapsulates how the metal attaches to the wood frame.

      Honestly didn’t spend much time thinking about it because I for one really like the sound of rain hitting stuff.

  • Dzintars Berzinskis

    Interesting. Can’t wait for the update 🙂

  • Mark

    Our office has moved away from wrapping gwb into the window surround and replaced with painted wood (poplar) for some added wear & tear protection. We will sometimes add a reveal at the joint, or tape & mus over the joint for a seamless look. Something to consider.

    • That is our typical detail in this instance 99% of the time but the owner expressed very strong opinions about no wood and no reveals. This is the result of listening to the client’s desire’s – which I am fine with, we talked through the impacts and ramifications and this was an educated decision on their part.

  • Jason Wolfe, AIA

    Very interesting – like everyone I love to see these details!

    I’m wondering why you decided not to do a flange around the perimeter of the boxes and screw them into the face of the structure rather than letting them extend back into the walls? Maybe it doesn’t matter so much in your climate, but I would be concerned about thermal bridging. We often have issues with condensation during the cold months if we have un-thermally broken assemblies.

    Great to hear about the process – really love to see how things come together in the real world. Thanks for sharing!

    • We did discuss that method of attachment but the concern was the expansion and contraction of the metal behind the stucco (which is the material where most of these aluminum boxes get installed). We didn’t want to get cracking through the stucco where the metal flanges would be in that method.

      Our climate is moderate enough to where we discussed the thermal bridging but elected to make that the lessor issue and not drive how we connected back to structure.

  • I too am curious about exp/contr. and I’d love to see a close up with the sanding complete. Thanks for sharing these details – we tend to be too selfish with technology and helps no one.

    • I will post a follow up once the stucco is installed. The sealant around the frame and the j-mold closure strip for the stucco should be nice and clean. The regular “irregularity” of the sanding should be about as apparent as your going to see in the 7th and 8th picture. These are the only windows accessible from the ground floor and I am standing about 15″ away from them when I took the picture.

      I vote for sharing when I get the opportunity.


  • Thanh Tran

    Great stuff!

    I wonder what the function of the 1×4 (between the masonry and sheathing) is, because I have never seen it in Montreal.

    • Technically you don’t need it in this instance – we included it to provide a secondary location for attaching the frame to the SIPs should it be necessary. More times than not we will include a 2x in this location when we are in a masonry wall so that we can bring the nailing fin of the window out and not have to include a masonry return. It allows the window to cover the gap between the sheathing and the masonry.

      • Pablo Serna

        Nice. Can you post a detail about that too? I really enjoy this part of architecture, btw.

  • gt

    Hey Bob,
    Nice post, as always when architecture meets technology and is well explained…
    So what about the head and sill details? I’m curious how you deal with the (seemingly) flat top of these boxes – what will stop water from penetrating?


    • The projection of the aluminum isn’t very much so you can’t really perceive that there is a pitch of 1/8″ per 12″ in place. I don’t think that standing water will be an issue but even if it is excessively slow to evaporate, since the stucco and brick masonry walls are not water tight assemblies, there is additional flashing that is in place as well as extruded polyproplyene copolymer weeps set at the head condition.

      I’m not overly concerned with water penetration but I am curious to see the extent the outside temperature has on the expansion and contraction of the assembly.

  • Craig V

    Nice write up and please tell the owner that the entire clan (dogs included) will be moving in once completed.

    • I’m sure once the matter of “rent” is resolved, they might be agreeable. I think there is one other person in the office here that has already offered their services to house watch … even when the home owners are home.

  • Good stuff, Bob! Love a good detail. I’d be interested to hear about how $150 per s.f. is achieved. Not that I don’t think it’s possible, just interested. So often we get wish lists a mile long with budgets that don’t match. Thanks, again!

    • There are a couple of moving parts to that question, total square footage helped bring that cost down, but we are using a cost effective window/door package, the exterior wall and roof assembly were done using SIPs, the finished floor is the post-tensioned slab, and the finish package was held in check. There are some other moves we made but its not for me to discuss them here (that sounds suspicious doesn’t it?)

      • Not suspicious, Bob…very familiar. All of it. In fact, we’ve made the same decisions on several homes here. All of the wish lists we get now include “high performance” items (tight, well-insulated, windows, efficient mechanical equip., etc.), but unfortunately the demand isn’t high enough to keep costs below $150 with typical finish, lighting and appliance wish lists. We’re finding a lot of opportunities in the design-build process, and our sub-contractors are getting used to this type of house, so they’re not needing to charge as much to do their work.