Home & Garden

About the House: Talkin’ Jack

By Matt Cantor
Wednesday January 07, 2009 - 06:34:00 PM

Every few days I pass a house perched ten or fifteen feet up in the air, waiting for a new set of roots to climb up and bolster its weight. 

There’s something very strange (and for me, fun) about an entire house; some one or two hundred-thousand pounds perched blithely on stacks of railroad ties. It argues with our sensibilities.  

Odd as it seems, it’s actually quite common. Part of the reason I see these so often is that I’m looking for them. It’s like blue Ramblers. When you’ve just bought one, you see them everywhere and prior to knowing about them, they may not have enough cognitive traction to obtain an imprint. You might not have ever noticed a house up on blocks but you will now. I guarantee it. 

Lifting a house is one of the easiest and most cost effective ways to increase the size of a house and it has a number of benefits to recommend it, especially if other circumstances align to its advantage. 

Lifting a house is most advantageous when a foundation already needs replacement since foundation replacement is nearly always required in order to lift a house. Let’s look at the cases in which foundation replacement are not likely to be involved since this set is much the smaller of the two cases. 

A house that is lifted but will have no living space below the original main floor may be allowed to retain its foundation if that foundation continues to be deemed adequate for support of the original structure. This is an odd case because it’s rare for someone to undertake such a burdensome (and pricey) task for nothing more than a taller basement or crawlspace and, frankly, I generally wouldn’t bother. 

It’s very occasionally the case that a foundation is adequate for support of another level of living space without costly modification but when it is, a house can be jacked up with only replacement of a taller set of supporting walls rebuilt over the foundation. This is so rare that I almost hesitate to mention it at all but there it is. It’s worth checking out prior to planning your project but don’t hold your breath. 

There are two areas of reasoning that lead us to the almost certain conclusion that a new foundation (or a major modification of the original one) will be needed for your heightened house and these are as follows:  

First is that the baseline design requirements for even a one story house foundation are unlikely to be met in your current foundation unless it was built in recent decades. Design requirements continue to become more stringent for foundations and a house from 1950 may not meet the requirements for a new house, particularly if there are soils or other geological issues. A 1930s house is virtually certain to fail to meet even the most modest set of modern standards and may not even be suitable for foundation repairs that, in a newer foundation, might allow for a height increase. 

The second set of issues has to do with the difference between one story and two story foundation designs (or the difference between two and three story, etc.). A one story house foundation is designed to bear a particular set of loads and if you add a story, it is very unlikely that modern engineering standards will allow that same foundation to serve for an additional story.  

Even in the case of the new lower floor being built as a slab (a concrete tablet that serves as both foundation and floor), where there is no crawlspace and the lower level rests upon the ground, the requirements demand that the lower level have a minimum ground clearance of eight inches and this, again, voids the use of most older foundations. While many variants from the ideal get built-out as finished basements, many have not actually passed building department muster and also fail the design requirement that modern engineering demands. In short, jacking up a house and planning for the lower level to involve dry living space is pretty sure to demand a new or greatly modified foundation.  

Since I keep mentioning modifications as one possible way to meet the support needs of the newly enlarged structure, I should give some brief impression of what this might entail. An upgrade can vary quite a bit, depending on the original foundation’s strength but one fairly common method is to add some sort of underpinning or an array of piers that beef up the original footing. These may be placed every few feet or yards along the length of the foundation or run the length of the foundation while grasping the original footing in some manner, typically from below as well as along the sides using epoxied rebar connections that become buried in poured concrete so that they become an extension of, and indivisible from, the original. 

There are other, more high-tech methods in use today, such as helical steel piers that can be bolted onto the original foundation. These latter methods may be very cost effective and are worth a look. Don’t expect every engineer to jump at these. Like contractors and architects, most have favored methods and many are slow to cozy up to every new product on the shelf (even if they’re good). 

Once you’ve overcome foundation issues, it’s surprising how little is left to tackle. The lifting process itself is usually in the range of 10-20 thousand dollars and may take only a few days to realize. 

Keep in mind that leveling is not automatically included and that you’ll have to ask for this when the house is lifted. Leveling will tend to crack plaster, bend flooring, change the shape of doorways and window openings and make lots of noise (SCREEEEEECH). All that said, I’d try to head toward level in nearly every case. It’s your one great shot at level doorways, floors and cabinets and it’s worth the repair of some plaster. 

One of the big losses or changes will involve the original stairways to the ground. These are, for the most part, toast. You may, in some cases be able to modify them (especially if you started out with a stand-up height basement) but in most cases, you should plan on replacement. This may be a moot point as the elevation of your house is likely to involve entry and exit from exciting new places. If your main floor is now your upstairs, you may not now be entering it from the exterior at all, and instead ascend between floor via a new interior stairway.  

And here’s a bit of a rub. When you go from one story to two (and so forth), you will generally need to cut away about 50 square feet from each of these floors to accommodate a stairway. Furthermore, finding the right place for this involves a special cleverness relegated to the better architects (as well as a few clever builders, homeowners or the odd inspector (don’t say it)). 

If your new full-height downstairs is approved as a separate living space (often a lucrative financial coup), you may, in fact, be retaining an exterior entry to the newly elevated main floor but again, the old stairway probably won’t survive the ascent. While you can take anything and push it up in the air, the criteria for stairways and porches are so much more stringent than they were, even 25 years ago, that few will be worth modification. Also, the cost efficiency of rebuilding or modification is always tenuous when compared with new construction, which has a domain’s worth of practical advantages. 

Electrical and plumbing changes are surprisingly simple when jacking a house, even with regards to temporary connections. Electrical systems mount on the side of most houses with “service drops” swooping in from a nearby power-pole. Raising a house has almost no effect on these connections and may not require any special attention in the short run, although the main panel will probably have to be moved down to a reasonable height as your project culminates. 

Sewer and water connections will require temporary extension pieces for the short run and then more serious alterations prior to completion of your new first level but these are fairly minor issues both financially and physically and should not be deciding factors in your decision to go this route. 

House elevation as a vehicle to expansion has a number of formidable pluses. Here are a few. When comparing house jacking to side expansion, zoning laws will often favor the former with regards to maximizing square footage on a given lot. The reason for this is that stacking living space leave more open space and the maintenance of open space is usually a major imperative in the calculus of zoning laws. 

Lifting a house and adding a floor to the bottom means that both roof framing and roofing material can remain untouched (unless you happen to need a roof). You’re just putting more people under the same umbrella. That can provide a major cost saving as well as the preservation of an authentic design element. And it’s one less job to think about (which is pretty nice when the rains start in the middle of your remodel). 

From a design standpoint, I particularly like the fact that older (and generally finer) architectural details are thrust upward above the newer, and typically, simpler, fatter or more mundane details that “found” or “ground” the structure. This has precedence in nature and is commonly mimicked in architecture. In short, it tends to look right. 

Building from the ground up is expensive. Adding a lower floor isn’t cheap either but, if you have the right set of circumstances and the right help, can be a truly ascended experience.