Home buyers ask themselves a lot of questions:  Can I afford this home?  Is it a good deal? Is this a safe neighborhood? Is the home big enough? Do I really need three bathrooms? But one nerve-wracking question often stands out as the hardest to answer: What don’t I know about this house?

No home is perfect.  Some come close, but it’s almost impossible to foresee during construction everything that could occur with the home.  It is even harder to predict the events that will affect a home as it ages. Therefore, when buying a home, whether it was constructed 1 year or 100 years ago, utilizing the proper due diligence is necessary.  During the buying process, having a home thoroughly inspected is always recommended to help determine common problems.  This visual inspection of the interior and exterior of the home can be performed by a certified home inspector.  However, most home inspectors review any documentation about the home and do not consider their inspection an “engineering evaluation.”  If the home inspector identifies a specific area of concern, such as structural cracking, old or faulty mechanical equipment, questionable or aged electrical wiring, an addition or basement finish performed by the seller, or even if the homebuyer simply feels additional information is needed, an engineer can evaluate a home in greater detail than the average home inspector.  A qualified engineer can research the home’s history, review the geotechnical report, review the original and any additional construction plans, and perform on-site observations of the home.  The engineer would then be able to explain any issues or concerns that arose with the homebuyer and review options to address those issues and concerns. 

Let’s take, for example, a home that’s a few years old.   The current owner and the condition of the house itself indicate there have not been any problems. There are no signs or reports of water leaks or mold.  There are no signs of design deficiencies or structural movement.  Most homebuyers would assume the house will continue to perform the way it has in the past.  However, many common problems in residential construction are issues you can’t see until it’s too late.  This is another reason why having a home inspection done by an experienced engineer can be an excellent investment.  The engineer will be able to pinpoint locations that could potentially create problems in the future, or problems that are already present with little or no outward signs.

One issue that can stay hidden is expansive soils below the home.  Colorado is known for its expansive soils and the damage they can cause to homes. The state of Colorado has statutes that require the disclosure of information pertaining to new homes built on expansive soils to prospective home buyers.  Colorado Senate Bill 13 (Soil and Hazard Analyses of Residential Construction - Disclosure to Purchaser) was created in 1984, and dictates that this information must be disclosed to potential homebuyers.  Another bill, Colorado Senate Bill 223, requires the same information be disclosed to potential buyers during the resale of a home.  This is one reason why reading and understanding a home’s original soil report is crucial to determining any potential problems.

A review of the soils report may reveal significant swell potential.  Now there is a new question to ask:  What was done during construction and what kind of maintenance is required to prevent the soils from affecting the structure?  If this question reveals that adequate precautions were taken during construction, the house may still be purchased without concerns of future damage.  Soil reports provide information pertaining to the soil types found on a site and recommendations for foundation types to be built on those soils.  If the swell potential is low, shallow foundations are usually recommended, as they are designed to withstand some minor soil movement.  If the swell potential is moderate to high, deep foundations are usually recommended in order to stabilize the foundation in stable soil like bedrock. The option is often given to remove the existing soils and replace them with soil whose swell characteristics have been predetermined as minimal and therefore can withstand a shallow foundation with a low risk of movement. 

One way to reduce the heave potential of expanding soils is to properly manage the water in the soil close to the foundation, primarily in the backfill zone.  At-grade materials should be sloped on all sides of the home to allow water to drain away from the structure.  A perimeter drain is typically recommended in the soil report for homes built on swelling soils.  If the perimeter drain was installed correctly it will provide a means of removing water from soils adjacent to the foundation.  If the home included a crawlspace, the perimeter drain may be installed with a sump pit and a sump pump.  The perimeter drain leads the water to the sump pit which is then removed by the sump pump.  It is the homeowner’s responsibility to periodically check the sump pump to verify it is working properly.  If a sump pump were to malfunction and not be attended to for some time, major problems could occur.  The excess moisture in the soils could create heaving conditions, causing structural movement and damage to the home as well as creating a high humidity environment capable of supporting biological growth.  Homebuyers need to be aware of the necessary maintenance involved with owning a home with a sump pit/pump system.

Example of settlement of expansive soils.

An issue that can stay hidden is water intrusion behind a home’s exterior cladding.  Residential homes are usually constructed with an exterior made up of one or a combination of siding, stucco, EIFS, brick, and stone.  All of these materials can be effective at keeping water out when installed correctly.  One way to help ensure water does not penetrate a structure is through the use of flashing.  The basic use of flashing occurs at intersections of two different materials, such as where siding would terminate at a brick ledge or where a stucco wall meets a sloping roof.  Proper flashing is one of the items a qualified engineer will look for.  If the flashing is not correctly installed, it provides the engineer information on where problems could occur.  Water can do a lot of damage to a house; that’s why engineers, architects, and builders strive to prevent water intrusion into homes.  Building codes ranging from local to international levels state that proper moisture protection is required for residential homes; however it is occasionally overlooked during construction.  Sometimes builders use all the right materials, but in the wrong order. In other cases, specifications or details called out in the plans could be misinterpreted or missed altogether.  Any of these situations could pose as a future nuisance for a home if not addressed. 

Example of lack of flashing resulting in water intrusion, trim damage, sheathing delamination, and possible biogrowth.

One other issue for potential buyers to look into when buying a home is efficiency.  With energy prices continuing to increase, homeowners need to ensure that they’re getting a highly energy efficient home.  A home inspection performed by a qualified engineer or home inspector can help determine the overall efficiency of a home based on the window and doors installed, weatherproofing materials, what type of insulation was installed, and several other criteria.  A variety of tests can also be performed in order to determine whether a home was built too loosely (where air exchanges easily from the interior to exterior and vice-versa), or built too tightly (where lack of ventilation can lead to interior air quality issues).  The blower door test is one method to measure how leaky a home is and where any leaks may be originating.  The basic procedure for this test is to seal off all exterior openings and then use a fan to pull air from the interior of the house to the exterior, creating a negative pressure environment.  By doing this, air leaks can be located by feeling for them, using a smoke pencil, or using an infrared device.  The results are then used to determine whether the house is too tight, too loose, or somewhere in between, and what actions can be taken to better the efficiency of the home.   

Purchasing a house is potentially the largest and most important investment people will make in their lifetime.  It is important to protect such an investment with vigilance and knowledge of any potentially expensive deficiencies in construction and/or maintenance issues associated with it.  Hiring a professional to evaluate visible problems, as well as to investigate the potential for hidden deficiencies, can assist a home buyer in making a wise choice when deciding to buy, or not buy, a home.

Copyright 2008. Professional Investigative Engineers. All rights reserved.