When Buyers begin viewing houses, one of the attractive (and more expensive) features is the walkout basement. A walkout basement is brighter, more useable / liveable, and provides better views, access, and egress than a standard basement. With all of these positives, why would every Buyer not want one?
Answer: many walkout basements (and homes built on slopes) have a proneness to serious structural issues. For normal houses without a walkout basement that are built on flat (i.e. non-sloping) land, the foundation is more or less equally distributed into the soil (i.e. at about the same depth) around all corners of the property. This means soil pressures imposed on the foundation perimeter are more or less equally distributed causing the house to be less likely to ‘shift’ or ‘slide’ in one direction or another.
For walkout basements, unfortunately this is not the case: the front of the house has strong soil pressures imposed, and these pressures decrease on a gradient to zero at the back of the house. This means at the back of the house, the soil pressures (i.e. imposed at the same height as the front of the house) are close to or at zero. With the imbalance of soil pressures, over time the front of the house is continually pushing the back of the house away from it and there may be rotational (moment) forces where the top of the house (both at the front and back) is rotating and moving at a variable distance than the bottom of the house (both at the front and back). The question for homeowners: why is this rotation and movement significant?
The answer: these forces, unless properly allowed for in the home design with extra special measures taken by the homebuilding contractor to counterbalance when building the foundation (e.g. on a piling system; and / or combined with strengthened walls, columns, and foundation; etc.), will create structural issues. These issues show up in the following ways:
(a). The sides of the house will have one or more large vertical / slightly diagonal crack or series of cracks where the back part of the house is essentially trying to pull away from the front part of the house. These same forces can cause roof and roof truss damage. Also: soil breaking apart (or slipping) in the sloped areas by the side walls.
(b). On the inside of unfinished basements the same vertical / slightly diagonal crack or series of cracks will be visible (i.e. only if the foundation is exposed – finished basements might hide damage beneath). Horizontal cracks indicate a much higher level of concern of structural issues and should be dealt with and repaired expeditiously without delay to avoid any serious structural failures from ever developing. Cracking can also yield water infiltration (may or may not be visible), both in the walls and the slab.
(c). On the back wall (i.e. the wall with the walkout basement door going into the backyard), the wall may show signs of pulling away leaving an exposed crack at the base of the wall right where it meets the slab.
(d). If there is a back patio, there may be signs of intense cracking or buckling of the patio bricks or concrete as the back of the house slides or pushes into it.
(e). If there is an elevated back deck with columns, the deck and columns may show signs of ‘rotational stress’ as well as shifting. Signs can include cracking around the base of each column; column rotation; shifting and cracking of the deck; column movement; and / or splitting (breaking apart) of each column.
So when buying a home with a walkout basement, aside from working with an experienced Buyer’s REALTOR®, my best advice for Buyers includes carefully navigating the important considerations below (conversely when selling a home, Sellers are advised to remedy all these issues before listing for sale in order to achieve a top market sale price):
(1). When viewing the house, observe closely for signs of structural stress in the categories above. [Note: for brand new homes that have not yet endured an Edmonton winter freeze-thaw cycle, the signs of structural stress may not yet be evident but may still occur within the next few years once the home has been exposed to freeze-thaw cycles. For this reason, Buyers must take extra special care and precautions for items 2 through 4 below when buying new / newer homes with walkout basements].
(2). Depending upon the amount of structural stress and soil (including improper grading) issues visible, make appropriate repair allowances in your offer to purchase. The cost of remedy (i.e. depending on the level of severity) can easily mount into the tens of thousands of dollars.
(3). Get the home carefully inspected by a highly-experienced licensed home inspector. Make sure your inspector uses infrared cameras and moisture detectors and demonstrates a specific knowledge of inspecting homes with a walkout basement including identification / remedy of serious structural issues.
(4). Before removing conditions, hire both a structural engineering firm and geotechnical engineering firm to assess and evaluate: (a). The structure; and (b). The soil (i.e. to ensure proper soil composition; water content; slope stability; and levels of compaction); and provide you with engineer-stamped reports of what remedies are required for successful long-term repair of both the structure and the soil.
(5). Before removing conditions, arrange a meeting with one or more qualified residential general contractors who specialize in the structural repair of homes with walkout basements. Ask for a complete time and cost quotation for supply and installation of all materials and services, including provision of all required permits and engineer-stamped 100% compliance certificates.
* Important Notes: (i). Homes built on a slope (i.e. even those without a walkout basement) will very often exhibit the same issues noted above due to the variance in soil pressures exerted around the perimeter. (ii). Homes built on slopes also can develop water drainage issues that should be evaluated separately. (iii). Other serious soil slippage cases include homes backing onto a steep ravine or river embankment.
Once Buyers have the above information in place, at that point an informed buying decision can be made. After all remedies have been successfully completed, Buyers should continually evaluate the home over their period of ownership and make sure that any new problems are repaired before any serious catastrophic structural failures are able to develop. My advice to handle this: hire back both the inspector and the engineers at minimum every 2 to 5 years to reevaluate and reassess the property.
Disclaimer: for those readers not currently represented by another licensed REALTOR®, to obtain more information on this topic and / or if you are serious about selling or buying in the Greater Edmonton Area, call Kelly at 780-414-6100 (pager) or send Kelly an email to SOLD@KellyGrant.ca to schedule a confidential appointment.
[Article written and ©2017 by Kelly Grant, M.Eng., ABR, NCSO, P.Eng. - REALTOR® at Maxwell Devonshire Realty in Edmonton, Alberta, Canada]