10 Reasons to Reuse an Existing Foundation
More and more in our residential design-build work, we’re reusing existing foundations. Even some of our projects that look like brand new homes have actually reused the existing concrete of a previous home on the site. There are a lot of important reasons for doing so, here are ten:
1. There are fewer blank lots available. Homeowners are more frequently purchasing lots based on location –even if there’s a home that they don’t want to live in on the lot.
2. Professionals have strategies. A good architect should be able to figure out clever methods to retain an existing foundation that accommodate the program of a new house.
3. It’s cost effective. Keeping the foundation saves more than just the cost of the concrete. It eliminates expensive phases like earthwork and items like exporting soil.
4. It saves time. There are usually still items to modify with the existing topography and foundation, but two major phases of a residential project are more or less removed from the schedule saving weeks or even months.
5. It’s more sustainable. The carbon footprint of moving earth and concrete around town is substantial. Not to mention the physical space that a demolished foundation takes up at the landfill.
6. It expedites permit reviews. Because the extent of work is reduced, often times, the permit scope will also diminish. Depending on the jurisdiction, the permit may even be considered a “remodel” rather than new construction.
7. There’s less bureaucracy. For properties classified as steep slope, critical areas, or slide zones avoiding earthwork can save a significant amount scrutiny from the building department. Less scrutiny directly translates into less paperwork, shorter permit review times and smaller permit fees.
8. It treads lightly on the land. Because of the diminished earthwork and site work, more of the existing environment can be left intact.
9. It lends discipline to the design. An existing foundation gives the homeowners and the architect a defined envelope to design within. The constraints encourage better problem solving; the designs tend to incorporate smarter solutions rather than sprawling floor plans to accommodate the new program.
10. Your neighbors will thank you. It keeps the site tidier, limits muddy tire tracks in the neighborhood and reduces noise on site.
Stay tuned for part 2 of the series which dives into our top 10 tips to assess an existing foundation.
By Henry, January 3, 2012 @ 8:38 am
Interesting strategy guys – thanks for laying it all out there. I would imagine that re-using a foundation is more prominent in urban areas where space is a little tighter.
By Lloyd Alter, January 3, 2012 @ 9:18 am
yes but, if the original foundation was designed for one storey and you add a second, how do you prove that the footings have the carrying capacity? How do you get the waterproofing on the exterior up to standard? When I used to practice, every time I tried to do this I ran into trouble.
By Build LLC, January 3, 2012 @ 9:34 am
@Lloyd -a good structural engineer (a typical team member on our projects) can determine the viability of reusing a foundation for a two level addition. A foundation that has standard dimensions can usually support a second level – more about this in Friday’s post…
The waterproofing depends on the location -if it requires full waterproofing we’ll dig out to expose the perimeter foundation wall and apply the waterproofing, footing drain, etc.
By Mike D., January 3, 2012 @ 10:59 am
Also, speaking as the owner of the house pictured above, how about the elimination of “settling”? A year and a half after moving in, I still don’t have a single drywall crack anywhere in the house. As I understand it, drywall cracks are almost a given in all new construction.
By Build LLC, January 3, 2012 @ 11:05 am
@Mike -great point! #11 existing foundations have already done most of their settling. This depends a bit on the new loads introduced to the structure, but for the most part the earth underneath the existing foundation has compacted nicely over the years.
By Graham, January 4, 2012 @ 3:00 pm
Its my present dilemma.. Great lot but late 70′s house in WI w/ 2×4 walls, and a garage that leads to the master bath. Foundation is solid aside from a Radon level of 4+ pCi/L.. mitigate or excavate?
By Margo Turay, March 10, 2012 @ 8:33 am
The guy who’ll use his skill and constructive imagination to find out how much they can give for the dollar, as an alternative to how little they can give for a dollar, is likely to succeed.
Sooner or later, champions are those who think they are able to.