Choosing Materials for Energy Retrofit / New Addition
Hello-
We own a 1958 brick home in Dallas, TX. We have added spray foam insulation to the attic. We’ve learned our walls do not have any insulation & our rooms get uncomfortably hot in the summers and cold in the winters.
We are in the planning phase for a remodel and addition to our home- we’d like to add 2000 sq feet to a 2000sq ft home. We would like to add high R value materials for our new addition. Also, we would like to bring our older half of the home to become more energy efficient.
I was hoping to gain input of the latest insulation technology & most cost effective to get to make for the most energy efficient home in terms of our exterior walls
(a) on the old portion of the home with brick walls – should we add cellulose in wall R-19; should we consider adding exterior rigid foam to the brick walls to add a higher R value?
(b) for the new exterior walls – recommendations on products to get the highest R value with the lowest expense
(c) for the crawl space (pier & beam home) – would you recommend additional insulation – cost effective?
(d) for the attic – what’s the most cost effective means in 2022
Thank you
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Replies
Mareddy,
Congratulations on the addition, and kudos for at least considering a more energy efficient path forward! There's enough material in your question for a short thesis worth of reply, but I'll do my best to give you some ideas to start looking into further, answering them a little out of order.
(D) The most cost effective attic, in terms of insulation, has been, and will always be blown in loose-fill insulation of either cellulose, fiberglass, or mineral wool, up to about 16" thick. If you search for "raised heel truss", you'll return a lot of results that show how a truss with a raised heel helps to evenly distribute insulation all the way to the outer edge uniformly, while maintaining plenty of space for ventilation, and storage if required. Here's a link to get started
https://www.apawood.org/raised-heel-trusses
There's a few reasons for this - (1) Loose fill insulation is easy to transport, is space efficient to transport, and is easy to install. The other is that it's the minimum area that can be insulated, compared to the sloped roof and possibly gable walls if it's not a hip.
(B) There are very many combinations of products that will work here, and much of it comes down to preferences. I may have missed it in your post, but do you have an idea about what the exterior finish of the new addition is going to be? Brick, stucco, stone, etc? That has some impact on the answer, but generally with 2x4 construction with a brick facade, I'd be tempted with the following stackups, for the money. From inside to outside
Wood version:
(a) 1/2 drywall (b) R13 fiberglass batts (c) 7/16" OSB or 15/32" plywood with taped seams (d) #15 felt or Grade D building paper (e) 2" Polyiso insulation (f) 1.5 - 2" air gap (g) Brick or stone of your choice.
If concrete masonry is dominant in your area, I would probably change that to CMU instead of the studs / osb, but the rest is similar.
You can build a better wall, with more insulation, or a stronger wall, or a prettier wall, it's all about optimizing what you want with a fixed amount of cash. The fiberglass cavity insulation is cheap, and the polyiso is more expensive, but it has a higher R value per inch, and mitigates most of the thermal bridging while at the same time providing something of a radiant barrier if you get the foil faced version. If your area is termite heavy, you may want to exchange that for something else, or look up the construction details that minimized the chances of infestation.
(C) Texas is a big place, and again this depends on your exact location. Are you in north or south texas, and coastal or more inland?
(A) There's a lot of ways to do this section as well. It would be a shame to cover up brick work (if it's nice, and you like it, and it's structurally sound). Is this a stud wall with a brick facade, or just a masonry wall?
dear kyle-
thank you so much for your detailed reply.
we live in Dallas, TX.
d) thank you for the information regarding loose insulation. our roof design at this point is more of a modern sloped roof or shed/skillion roof with eaves & a front area with a flat roof - in our current home we have spray foam insulation - we like it as it seems to keep the temp down in the attic while also allowing for attic storage space. how does spray foam compare to cellulose in price?
b) thank you for the ideas of the new insulated wall will consider what you mentioned. not
sure about the termite infestation in our area. exterior finish - we were thinking composite wood (new tech) mixed in with cement board or stucco or brick - not finalized yet.
c) crawl space - we are in Dallas
d) this is a wall with wood studs and masonry on the outside. I was thinking of densely filling the walls with cellulose. however wondering if further insulation would be helpful. Yes the brick is a great finish but I thought it may be cheaper to add additional rigid foam to the exterior brick rather than add to the interior walls.
mareddy,
I'm not sure how it compares in your area. I'm sure that's very regionally dependent, but generally cellulose is cheaper than closed cell spray foam, if there are installers around.
Regarding the crawl space, I think the current best advice is to make it sealed, and part of your conditioned space. The current featured article is a good place to start. (https://www.greenbuildingadvisor.com/article/how-to-minimize-moisture-in-a-crawlspace) .
Thank you Kyle!
I don't feel your objective is to fix and patch like the HGTV shows, which IMO, they are all lipstick on a pig shows.
You can drive around Dallas and see hundreds of old houses being torn down to build new ones, and the reason is because to remodel and make such a large addition to a high-performing house is complicated and very expensive, more often than not, over a new build, at least I get the impression from your post that you want it done right. I know, I've done tens of these projects here in Dallas, and currently working on a handful around the Park Cities and White Rock Lake.
Make sure you consult with structural engineers about your pier foundation, and if it can support a second story; they seldom do. You may know that our soils in these areas are very expansive and move a lot. You probably need to fix, clean and encapsulate the crawl space. More than likely, you need all new electric and HVAC system. Your old walls may need to be stripped to the studs in order to install sealed sheathing and rigid foam, as those walls were never sealed or had good moisture management.
Make sure you have really good information before you make your final decision.
Hi Armando - greatly appreciate your post and advice. We have reputable architect helping us & will certainly have soil testing as well as a structural engineer. We are in the initial process of design & plan on bringing a builder to help guide as well.
I understand what you’re saying about working with something old & expense of countering old products. However, in the spirit of green building, recycling, preservation- much prefer to think renovation and addition instead of demolition and wasting products that could be of use. But we may have to go that direction.