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Soliciting feedback on a potential home purchase

david_solar | Posted in General Questions on

Hi All,

My wife and I have decided to purchase our first home rather than build because we’re not certain we’ll be in it for more than seven or eight years. I’ve been reading here for ages so I have a file folder full of notes on how to properly orient a home, how to size HVAC with Manual J calculations, the PGH concept of 20-40-60 insulation for the foundation-walls-roof, putting enough solar on the roof and forgoing a gas hookup, and all that good stuff. So, when my wife and I found a house we both liked, I reached out to the builder for some details on the construction and he responded promptly.  The house looks like it was built to code minimums, but since we’ve only ever rented apartments in cities, I don’t actually know how much these things will affect our comfort. For reference, the house is in Climate Zone 5A. Here’s what I’ve learned:

1) Wall framing from the interior out: 1/2″ drywall over 2×6 douglas fir studs, R-21 fiberglass insulation with 4-mil poly or kraft paper vapor barrier, 1/2″ 5-ply fir sheathing, air infiltration barrier, and vinyl siding

2) Foundation is uninsulated, 6-mil poly vapor barrier under the slab, but at least it’s built with good concrete and not the stuff that’s crumbling all over Western MA from a bad quarry.

3) The ceiling of the second floor has R-38 blown insulation and the unconditioned attic rafters are insulated with R-30 fiberglass.

4) The HVAC contractor “ran heat loss calculations and sized the system accordingly,” although I need to confirm the size of the hardware.

5) The electric utility told me the average monthly bill over the last 12 months was $187 (I know this is occupant-dependent).

6) The gas company told me that the summer months ran $30-35 (I’m assuming just for the connection fees) and that the winter high was $308 in February.

Knowing all this – and knowing that pretty much any stick built home will be built similarly – how much should I really be stressing about it? Any advice you guys can offer is greatly appreciated. Thank you!

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  1. MattJF | | #1

    As long as it is the right size and location for you, you will be financially ahead by doing practical energy retrofits on this house.

    The only thing that sounds a little funky is the 2nd floor insulation. Are there really bats on the rafters that form the roof? Are there ventilation baffles above them? Why didn't they just blow in R60?

  2. Expert Member
    BILL WICHERS | | #2

    Sounds pretty typical, and not bad. I agree with Matt that the roof/attic insulation is a bit funky. If this is a vented attic, there is no point to insulating the rafters and the attic floor since the attic itself is not conditioned space. You might want to ask about that. If it’s a normal, vented, attic, you can easily and cheaply blow in additional insulation to get up to the total R value you want.

    I ask about if the walls were built with poly sheeting (a vapor barrier), or kraft paper (a vapor retarder). I’m assuming they did things correctly, but this is something that you should know for sure since it may have an impact on things you’ll want to do in the future.

    You have poly under the slab, which is a good thing. Adding rigid foam basement insulation on the inside is an easy DIY project that you can do when you have the time. This is a simple upgrade you can make.

    The utility costs don’t really mean much without knowing at least the square footage of the house. Im guessing that this is a good-size place, probably 3,000+ sqft, unless the previous occupants were heating to tropical temperatures inside.


  3. GBA Editor
    Martin Holladay | | #3

    Home buyers like you are in a tough spot. Most homes are built to minimum code requirements -- or less.

    It's up to you to decide whether you want to pay for a detailed pre-purchase inspection -- perhaps with a blower door and infra-red camera, if the seller agrees.

    This month, I've responded to several GBA readers who recently bought a home, only to suffer massive ice dams the first winter -- ice dams that damaged interior finishes and require tens of thousands of dollars in roofing work, air sealing work, insulation work, and interior repair. These stories are depressing. Poorly insulated roofs are not a "so what" issue -- these issues can bankrupt a family. No easy solution.

  4. Expert Member
    Dana Dorsett | | #4

    >"The house looks like it was built to code minimums..."
    >"2) Foundation is uninsulated..."

    In MA R15 continuous foundation wall insulation is required (on either the interior or exterior) if it's a poured concrete basement or crawlspace, R10 continuous slab edge insulation to a minimum depth of at least 2 feet below grade if slab on grade.

    >"3) The ceiling of the second floor has R-38 blown insulation and the unconditioned attic rafters are insulated with R-30 fiberglass."

    That is not a code-compliant assembly on an R-value basis. If the attic is insulated at the rafters it needs to be R49, though R38 at the rafters can be compliant if thermal performance is assessed on a whole-house performance basis. The R38 on the attic floor does not count (AT ALL) if there is R30 at the rafters. It's not legitimate to add them together and say "Higher than R49 total? Yup, we're good!

    Are there there any ducts or air handlers etc in the attic, between the R38 floor and the R30 rafters?

  5. user-723121 | | #5

    $308.00 for gas (natural?) for February is a lot. I would guess this house has a very high infiltration rate.

  6. david_solar | | #6

    Thanks everybody for the replies. I've found a contractor to do the infrared / blower door testing, and potentially test for HVAC leaks as well.

    I'll follow up with the builder for additional information about the 2nd floor ceiling / attic / roof insulation details, as well as confirmation that the exterior of the basement slab isn't insulated because the interior sure isn't.

    Dana, thank you for the specific mentions of the MA housing code. This house was built in 2015, so it probably didn't need to meet code at that point. The two neighborhoods we're looking at were built by a single builder, so presumably all of the houses are constructed similarly. Maybe if we can validate that it's leaky and confirm that things aren't up to code, we can at least negotiate the price down to reflect the cost of addressing them. Seriously - thank you guys for the assistance!

    1. Expert Member
      Dana Dorsett | | #7

      >"This house was built in 2015, so it probably didn't need to meet code at that point. "

      Sure it had to meet code, just not IRC 2015.

      In 2o15 Massachusetts statewide was still operating under the 7th edition of the state building code based on IECC/ IRC 2009. Some cities & towns had "stretch code" requirements at that time bringing it to IRC 2012 level R-values, which are identical to those in IRC 2015. (You would have to look up whether your town was under the stretch code. Most or all of the "Green Communties" had made that change prior to 2015.) The 8th edition Massachusetts code based on IRC 2015 didn't take effect until July 2016.

      Under IRC 2009 the R38 on the attic floor would be compliant if the attic is vented. But the basement & crawlspace foundation walls needed to be a minimum continuous R10, and slab on grade needed to be R10 down to a depth of 2' just as now.

      Though the attic might have made it, the uninsulated foundation didn't.

      1. david_solar | | #12

        Dana, in case you're interested in an update, the town building inspector told me that so long as the basement is insulated "somewhere", it passes code inspection. In the case of the home we're buying, the ceiling of the basement is insulated to R-13, and while that puts the entire basement outside the envelope, it's good enough.

        Ensuring the exterior drains away from the foundation, sealing the concrete floors, and insulating the interior walls are all on our to-do-list once we've closed. Thanks again for the guidance.

        EDIT - specificity never hurts. The 2009 IECC states in section 402.2.7 that basement walls must be insulated, unless the ceiling of the basement is insulated per prior sections, and those prior sections call out R-13 for basements.

        1. Expert Member
          Dana Dorsett | | #13

          >"In the case of the home we're buying, the ceiling of the basement is insulated to R-13, and while that puts the entire basement outside the envelope, it's good enough."

          The MA version of IRC 2009 called out R30 for floors over uninsulated basements, not R13. If R30 doesn't fit between the joists, whatever actually does fit is required. R19 is absolute minimum even if it doesn't fit (which would be some pretty thin joists!), found in footnote "g" of Table 402.1.1

          If there are heating/hot water pipes, water heaters, furnaces/boilers etc in the basement insulating the ceiling can even increase net energy use, but a lot depends on the particulars.

          1. david_solar | | #14

            Building codes are confusing! You're right, of course, that I should be looking at the values for the floor of the lowest space in the envelope, rather than the ceiling of the space outside the envelope.

            You also might not be surprised to hear that I don't want to pick a fight with the town's building inspector when clearly dozens of buildings he's passed for inspection don't meet code minimums...Dana, I know you have a day job, but do you consult on the side?

  7. Expert Member
    ARMANDO COBO | | #8

    A resent Rocky Mountain Institute report, a 2200 sf, 3 bed, 2 bath house in the 50 biggest cities in the US, excluding climate zones 1 & 7, shows that a Zero Energy Ready home is costing around 1-3% more to build. In Boston, the incremental build cost is $1837, with annual energy savings of $658. That means that in less than three years you pay it off, and have savings for the rest of the time you live there.
    The idea that a high-performing house cost a lot more to build is not true, at all. Also, all our ZER homes are well above code. All you need to do is research for an experienced, high-performing builder in your area. There are no excuses anymore.

    1. MattJF | | #9

      If you have a builder who knows what they are doing, building an energy efficient house is not substantially more expensive. Most houses are not custom built one offs. For the OP, you need to consider that their situation is buying a 4 year old house vs building one. I would say that it is VERY challenging for someone without significant building experience to build a one off house that is cost effective long term vs existing housing stock.

      In Massachusetts, code enforcement in many towns is substantially out of sink with what is on the books. My 2008 built house is even missing code compliant railings on a couple sets of stairs. The town building permit paperwork has weird things when we get to energy/HVAC topics like a new furnace requires a manual D (They should be asking for a Manual J and S and maybe a D). This is North Shore, not even small town Western, MA.

      1. Expert Member
        Dana Dorsett | | #10

        >"In Massachusetts, code enforcement in many towns is substantially out of sink with what is on the books."

        No kidding! The quality of the inspection/inspector does vary. I can't really say how many houses I've seen in Massachusetts where the R15 insulation on the exterior of foundation stops at grade rather than continuing on up to the foundation sill. But even those are better off than those going in with no foundation wall insulation at all, despite having been a requirement (for at least R10) for nearly a decade now. Somehow the houses get signed off and sold despite obvious shortcomings relative to current code. Sometimes the code inspections are performed by former builders with long standing good-old boys club type relationships with other builders in the area.

    2. david_solar | | #11


      The issue isn't the cost of building a house - I've talked to a local high-efficiency builder, GoHomes, and Brightbuilt and could definitely afford a tightly-built new home. The issue is getting a piece of land to build on. I'm in Massachusetts, and I've got two children who'll be attending public schools. I've also got a wife whose employment contract limits her to a specific range from where she works because she's sometimes on call. We don't want to live in a rural town, or a town with poor public schools, so it severely limits where we would build. The lots in the towns in which we would live all go for $200k at the low end, and then you're dealing with $7-800k all in before landscaping. There aren't any cheap teardowns in these towns, either, unfortunately.

      1. JC72 | | #15

        I feel your pain. Land costs are a primary driver in the cost to build. It's why we see new homes which take up as much of the lot as possible. This is especially true of in-fill lots because they are typically smaller.

    3. JC72 | | #16

      Ya I'm not so sure. With the vast majority of new homes being built in PUD's and the fact that orientation plays a role in energy efficiency I can envision ZE houses creating a limit with regards to the number of units a builder can place on the property while also maintaining some semblance of a "neighborhood" feel. Consequently I didn't see in this report where higher prices due to the reduced number of units were considered.

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