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Community and Q&A

Basement rebuild

kenmarcou | Posted in Green Building Techniques on

I was wondering about the feasibility of building a new basement as if it was a new high performance building and then either demoing and placing a modular home on the new basement or stripping the current house above the new basement down to the timbers for a gut remodel.

It’s a zone 5 rural central MA house built in 1840. Impossible to heat. Basically a glorified barn. Whole house is about a 800 Sq foot footprint with 3 levels. Walk out basement w/the above grade wall facing south. That brick wall needs to be replaced. Most of the basement floor has always been dirt. There’s water problems and mice and cold and it’s all bad. The sill in the back in the hill needs to be replaced also. If I don’t demo I’d need to jack up the house for that anyway so I’m wondering if I can do this renovation in stages starting with the basement completely redone like it’s a new build. – Build an insulated basement slab and insulated below grade walls properly water managed on the exterior of the walls by widening the hole in the hill a little to do drainage and dimple mats etc. – Build the front and side above grade walls out of wood on footings and insulate and air seal. – Redo the sill plate at top of basement wall all the way around. 

From there id at least have the old house sitting on a non-crumbling foundation, mold sources and pest infiltration would be mostly solved and it would be warmer from not having the stack effect pumping cold air from the basement and earth up through the house for starters. The old house from there could be gutted or demolished for a new modular home on the brand new high performance basement. 

Id love thoughts on this! Thanks so much. 

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Replies

  1. Expert Member
    Michael Maines | | #1

    Unless there is a lot of historical merit to keeping the old house, I would either keep updates to a minimum or start over with a new frame. There's just not a lot of inherent value in preserving an old house frame if everything else is going to be replaced. House frames of that era are seriously undersized by modern standards so you would have to do a lot of reinforcing to meet code requirements with that scale of a renovation. It's usually more expensive to jack up a house and to excavate and build a new foundation under it than to demolish the house and build with nothing in the way. But if you want to do a lot of the work yourself, want or need to tackle it piecemeal, or you want to keep as much of the old house as possible for sentimental reasons, you can certainly do as you propose.

  2. steveoneil | | #2

    I had a new basement constructed under my existing old house.
    Sounds like a similar situation-- mine is an old barn, converted to house in the 70s. It had a stacked stone foundation and essentially no crawlspace. Very cold and drafty, with no good way to fix it-- not enough room to get under there to air seal and install insulation. At the time we wanted to keep the unique features of the barn itself, and also needed a place to live, so we ruled out demo and rebuild. To make a long story short, we ended up having a full basement installed. I made sure to build it with energy efficiency, resiliency and future living space in mind, so I have sub-slab insulation, exterior water proofing and insulation, rough plumbing and egress windows. This was completed about 9 years ago. Based on my experience, my advice is this: DON'T DO IT. I thought I was doing the right thing to preserve an old building with some unique features, but it ended up being a tremendous waste of money. In retrospect, the best course of action would have been to build a new house on my lot and demo the old one. That or just sell it and move on.

    1. Expert Member
  3. nynick | | #3

    I'm about to renovate a house built in 1850 with additions put on later. It doesn't sound as bad as yours but it'll be a total gut job including roof, siding, windows....everything. With the current cost of construction I could probably come close to the same as brand new construction costs versus a renovation. There are mitigating factors as to why we chose the renovation, but the prices aren't all that different if you need to do as much stuff as we do.

  4. plumb_bob | | #5

    A house that has been occupied for over 100 or 200 years has reached the end of its useful service life, and no amount of money or effort will make it as high performance as a new build. It is difficult to integrate the old materials and systems into newer materials and systems, there is always trade-offs on performance. Most everybody that goes through the huge effort of restoring an old house regrets the time and money spent when compared to building new.
    I suggest that some effort be put into salvaging some of the wood and other unique ornamental features from the original house, these can be used in a new build in the form of furniture or other custom works. The old house can live on.

  5. kenmarcou | | #6

    Thank you all for sharing these insightful experiences and thoughts. Demolishing has always seemed to be the way to go. The house has old large 10x10 and 12x12 timbers as framing and seems like it's valuable wood so the idea of knocking it down and throwing it all in a landfill seems like it is...not green to say the least. But "deconstructing" to save the old valuable old wood bones is a lot more expensive than "demolition". Anyone know of ways to handle this and not break the bank or even be a net positive?
    Getting all the funds for everrrrryyything all at once is harder - I would've been able to swing the foundation without any financing and then maybe financing out in the world would be in a better place in a couple years for the demo and rebuild of the house on top...this sort of thing was my thinking about this post. Any insight about not having production builders who hire overworked and rushed subs to do a bad job on the new build as well as having a say in how it's built without a luxury custom build route would be appreciated. Seems like high quality modular's are the best route.

    1. nynick | | #9

      Let me add some thoughts. I have renovated a few personal homes and done some large projects DIY. I'm fairly handy but know my limitations. You can get a lot done with considerable savings by taking your time, doing things yourself and hiring out sub-contractors when needed. The subs are always the least dependable, screw with your schedule and can be risky quality wise, but if you do your homework and check references well you can pull it off. Paying cash helps.

      The more people you involve the more complicated it becomes. A reasonable architect is worth their weight in gold. You want to be sure the building is safe. The actual construction thereafter isn't rocket science. Take your time, buy the right tools, develop a relationship with a lumber yard and have a go to helper. Watch a lot of youtube.

      If you go with a manufactured home, there are some really great ones out there but when all is said and done, you'll still need most of the trades to help with the project. These homes aren't cheap, but you get good quality and value. If I was building from scratch again, I'd probably go this route.

      Just as a FYI, I interviewed and spoke at length with 5 builders/GC's, sent them plans and had follow up calls with them. 4 of them never got back to me. 4! WTH?

      The world is a different place these days. These guys are plenty busy and very choosy about the jobs they take. Subs too. Good luck!

      Nick

    2. Expert Member
      Dana Dorsett | | #10

      >"Thank you all for sharing these insightful experiences and thoughts. Demolishing has always seemed to be the way to go"

      If there is plank sheathing under the siding and the windows aren't rotted it might still be cheaper to deal with it as a restoration, only gutting the interior. If the floor plans suck and the stairs are out of code to a scary degree it might be trash-able.

      About a decade ago I got sucked into advising on deep energy retrofit (DER) on a 3 story 1890s farmhouse in Worcester MA. It had been converted to a 3 family at one point. The siding was shot but the broad-board plank sheathing under it was in good shape, and the framing was still reasonably straight and square. The interior was a mess, and needed to be gutted to the studs to deal with cosmetic (and lead paint) issues. The antique windows were salvageable but would not meet the performance requirements of a DER. But stripping and replacing the siding allowed for installing U-0.19 new-construction type triple panes (something that will never pay back on energy use, but OK.)

      The brick foundation was repairable/salvageable, and insulated on the interior with a few inches of closed cell spray polyurethane. The basement had no structural slab, only a partial 1-2" rat-slab over about half. It was dug by hand down about 6" (college football players from Holy Cross University are cheap! :-) ), a couple inches of foam board laid down & taped, and a proper slab poured.

      The pre-existing cavity insulation in the balloon framing was a blown cellulose installed ~1980 and still in good shape, but for air tightness purposes the owner opted to clean it all out and foamed the wall & roof cavities with closed cell foam (I was advising against that on both environmental and cost ground), and 4" of polyiso foam board- 3" reclaimed roofing foam, with a 1" additional layer on the exterior was foil faced lower density sheathing foam. (By going with reclaimed foam it saved well over 10 grand.) Similarly there was 7" of reclaimed foam installed on the roof.

      In the end it was possible to heat & cool the place with ONE ductless minisplit per floor (3 total). Even though the load numbers indicated 1-tonners would make it, both the HVAC contractor and owner were nervous enough about it to go with 1.5 tonners. Each floor had a separate and appropriately sized heating ventilation unit.

      No it wasn't cheap, but there is absolutely NO WAY simply knocking it down and building something new at that performance level would have been cheaper (even without factoring in the DER subsidy money being offered through the utilities at that time.)

      A short writeup and description of that project by the utility was captured and still lives on the GBA website:

      https://s3.amazonaws.com/greenbuildingadvisor.s3.tauntoncloud.com/app/uploads/2013/04/08094831/Worcester%20Open%20House2013.pdf

      If you're under one of the bigger utility companies (either gas or electric) there is still substantial subsidy money for different aspects of upgrading an antique house like yours.

  6. seabornman | | #7

    I'll be the outlier here. I've added onto my ca. 1840s house and then renovated existing including tearing all of the exterior walls down to framing, installing new sheathing, windows, exterior insulation, siding, and new metal roofs. I've kept 1/2 of the interior rooms somewhat intact. I added ground source heat pump system 10 years ago, so I have a reasonably high performance house. A staged approach has kept me from having to permit and inspect the work, and the tax man hasn't yet reassessed me for the whole thing. I feel it was well worth it.

  7. steveoneil | | #8

    kenmarcou,

    My situation was probably worst-case-- we had to excavate for the new foundation. After re-reading your post, I realized I missed that you already have some sort of basement, and so maybe the excavation will be minimal. But I was thinking along the same lines as you-- a new foundation was affordable to me without a loan (initially) and I figured once that was taken care of the above grade portions could happen over time. After all, a good house starts with a good foundation…
    Here are the highlights and then I'll tell you where I ended up:
    • During excavation, bedrock was hit, requiring splitting and removing of ~ 70 yards of rock. This slowed everything down and greatly complicated things, not to mention the added expense.
    • Overall, the project ended up costing almost 3x the original price
    • I did a lot of work myself at the end
    • It took almost 3 years to finish
    I now have a very nice basement, which will be converted to quality living space, eventually.
    Since the basement was finished, I have been working with architects and engineers to design and draw up the above-grade renovation.
    Years of planning, a generous budget (I feel) and 10's of thousands of dollars later in architect and engineering fees, everything was ready--just in time for the pandemic. Contractors got busy, lumber prices went through the roof, and this is a unique and large project, which turns out, no one wanted to touch. After wasting literally years trying to get a contractor lined up, I said F-it. I'll just tear the whole thing down and build a kit house on the existing foundation. So I went that route-- got a post and beam house custom designed to fit on the original footprint. Thought I was good to go, then two contractors disappeared on me after discussing the project in length. So another $17k wasted in design plans and no one to build it. So at this point, I decided the only way forward is to DIY. No idea how long it will take, and I will hire out things I don't feel comfortable doing, but at least progress is being made, finally. My goal is a better-than-average performing house-- using double stud walls for thick insulation. I will go room by room and be meticulous with details. It probably won't be as good as a new custom built high performing brand house, but I'm sure it will be much better than the average house in this area. I'm in eastern MA, FWIW.

    I wish you best of luck with your project, whatever you decide!

    Steve

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