BELLEVUE -- We are purchasing a house in Snoqualmie Ridge, WA. The house was built by Conner Homes (http://www.connerhomes.com/) in 2006. Conner Homes is a reputable company. So, given the age of construction, the expectation was that the house would need minor repairs. However, the house inspector we used (Architectural Building Inspection, Inc., one of the most respected building inspection and consultation companies in the greater Seattle area, known for the high quality and thoroughness of their services, in business for almost 30 years http://www.abi-bldg-insp.com/) found several issues with construction that need to be addressed.
These issues are structural in nature and originate from a faulty construction. These issues were either not caught by previous inspectors or were not visible until the elements in question failed. We think Conner Homes, the builder, should address those issues given they should have done so in the first place. The issues are the following:
SIDING: In spot checking the horizontal lap siding, I found the gap between the siding and joints to adjacent components does not comply with manufacturer's instructions. This is not too critical, but contributes to bowing and irregularities. Joints between window frames and siding are not caulked as required by most window manufacturers and current code. It is important to keep siding well caulked to prevent water infiltration and reduce air
infiltration/heating costs. Caulking needs to be installed.
Code requires exterior wall perimeters to be sealed, including areas with siding. In spot checking these areas, I found some gaps (e. g., deck underside adjacent to strip vents). Gaps are conducive to unnecessary air infiltration and potential leakage, and they can allow insects and small animals to get into the building. The entire perimeter needs to be checked, and all gaps sealed. In spot checking the exterior siding flashing, I observed various inconsistencies as follows:
1) The sheet metal counterflashing at the horizontal trim slopes back into the building. This is technically undesirable because water can accumulate, run laterally into flashing joints, and leak into the building. It would be appropriate (and relatively simple) to correct this by adjusting the trim/flashing.
2) Siding trim at vertical component connections to horizontal components were installed without overlap (i. e., window perimeter wood trim and components), so water that drains down the face of these pieces can leak in at the joints and behind the material itself. The horizontal ledge trim does not have overlap, counterflashing, or a drip edge at its outer edge, so water can leak into the underlying joint. In spot checking, I did not observe indications of significant leakage. Given the conditions, it is not imperative to rebuild this area, but important to keep it sealed with very good quality caulking and painting.
3) Exhaust vent exterior wall caps and other utility penetrations do not have proper flashing at the siding, which is very conducive to leakage into the open horizontal top joint. Unfortunately, this is fairly common. Ideally, proper counterflashing should be installed to correct this discrepancy, but if it is not, keep the area well sealed with caulking. In spot checking, I did not observe indications of significant current leakage or damage.
4) Some horizontal trim (e. g., deck column bottom) is not properly beveled or flashed. The horizontal trim projection tends to catch water, and can, in turn, allow it to infiltrate the siding. It would be advisable to correct the beveling and flashing to reduce the risk of leakage.
Remedy: It would be advisable to have an experienced and qualified siding installer completely check the exterior siding and develop a scope of corrective work, various alternatives, a cost/benefit evaluation, and cost estimates for corrective work. It is important to attempt to improve the exterior siding because resultant leakage will cause premature paint failure and increase the risk of other problems.
EXTERIOR PAINT. The quality of the exterior paint workmanship aspects was inconsistent. Various areas of wood trim did not have appropriate second and third coat applications; some has failed. Further, the exterior siding caulking and paint utilized were not compatible, so there are "stretch marks" on the paint film surface. This is not technically critical but mainly a visual factor. Additionally, the wood shingle paint coating was not ideal, and at shingles' surfaces the face end grain (that tends to soak in more paint) was such that the application was not uniform. Remedy: Some Areas need repainting and touchup.
EXTERIOR DECK. The main floor back deck has a membrane floor surface, the configuration of which is very good in and of itself (i. e., provides roof shelter to overlying area). The installation quality of the deck membrane, flashing, and venting is poor and corrective work is needed.
The deck floor was covered with a fluid-applied elastomeric membrane (a protective "skin" composed of a polymer compound with elastic properties). The installation does not comply with manufacturer's installation recommendations and/or good construction practices. This will cause premature deterioration and potential membrane leakage, and it will probably need to be replaced sooner than it would if it had been properly installed.
The membrane underlayment was not properly installed in terms of gapping and material. Consequently, the underlying panel edges are "telegraphing" up to the membrane (this is symptomatic of failure of the substrate underlayment base). Further, I would anticipate the quality of the underlayment was fair, and it is experiencing some abnormal thermal and moisture movement. Some of this is also a result of inadequacies with the underlying venting and flashing (see related points below).
The estimated serviceable life of the deck membrane is 0 to 5 years. The 0-year estimate basically means that the deck membrane should be replaced as soon as practical. It could be patched, and replacement deferred for a few years, but this option will put the deck at risk of leakage and damage. If replacement is deferred, the membrane needs remedial service work (patching) and needs to be monitored carefully for leakage.
The decision as to when to replace the membrane should be, in part, based on what you intend to do with the building (e. g., exterior repainting). Note that, given the membrane's present condition, some ongoing recurring leakage is to be expected. This will cause some further damage, but its extent should not be too significant, so it would be a reasonable risk to defer replacement.
The membrane flashing connection into the adjacent guardrail post, as well as the connection into the sliding door sill (plus, I suspect, underneath the siding) was not appropriate and the connections are vulnerable to failure. The connection between the membrane and door sill bottom has failed (disconnected), which is conducive to water and moisture leakage underneath the membrane.
The amount of venting provided for the wood frame under the balcony floor is marginal (about 70% of what is required by current code for deck or balcony areas that have no overhead roof protection). The
amount of venting required by code is technically minimal. Venting should be improved to reduce moisture/rot damage from inevitable leakage. The situation is potentially critical in terms of damage caused by leakage, so it is very important to monitor the area for leakage.
One of the fundamental problems with the venting is that the prefabricated metal vent strips installed have a very negligible net venting. Replacing the existing punch sheet metal strips with a "¼" screen would provide the deck with 5 times its current net venting.
Code and manufacturers require balcony floors to slope a minimum of 1/4 inch per foot (2%) for proper drainage. In spot checking, I found that slope was generally 1.5% to 2.0%. This does not comply with manufacturer's instructions and code, which typically voids a manufacturer's warranty on the serviceable life of the membrane surface.
Fortunately, the slope is reasonable, and in spot checking, it appears that water is not ponding on the floor surface. If there are low spots on the floor where water can pond, minor defects at ponded areas will result in leakage through the membrane. Water ponding is very risky and, when it occurs, leakage is to be expected. The existing situation reduces the serviceable life of the membrane; other factors also affect serviceable life (i. e., proper venting, proper maintenance of the surface, and preventing leakage into the membrane from adjacent siding components).
Current code for guardrailing stipulates 200 pounds concentrated load at any point along the top rail edge and 50 pounds for any one square foot within the rail top (for commercial buildings, guardrails accessible to the public: 50 pounds per linear foot applied in any direction at the top is required, and for others not accessible to public, 20 pounds per linear foot). It is important to monitor the guardrail for strength.
GARAGE STEPS: There is a significant change in step vertical dimensions, which does not comply with code.
Further, the step dimensions are non-standard, making them a significant potential tripping risk. It would be advisable to install a platform type landing step with equal vertical step dimensions. Further, the interior door sill is too high and does not conform to code (maximum 1-inch height).
SHOWER SURROUND IN MASTER BATHROOM: The quality of the shower surround and bench tile is fair. The tile wall surround is loose, and I suspect that its backing board is deteriorated and will need to be repaired. It is very possible that the adjacent wood frame is deteriorated and will need to be repaired as well. The full extent of any frame damage that may exist cannot be determined until the surround is removed (other finishes may also need to be removed).
I did not determine what the base wallboard for the shower wall surround is. Ideally, it would be a masonry installation (e. g., cement board). If it is a gypsum board product, keep in mind that they are more vulnerable to leakage/deterioration and, as such, it would be important to keep the surround surface wall maintained. The horizontal bench and adjacent components need and underlying waterproof membrane installation, and I would anticipate that this was not done.
ROOF VENTILATION: Roof vents are inadequate and are not in compliance with code requirements. I did not do calculations, but based on my observations I would anticipate that the installed vents provide about 40% overall of what current code requires. Furthermore, the amount of venting required by code is technically minimal. It is very important to have a vent calculation done and install additional vents to correct this discrepancy. We have found that continuous ridge vents are very effective and are relatively economical to install (usually around a 2-year payback period).
Roof framing needs to have good screened vents to dissipate hot air and moisture buildup. Without proper venting, temperature buildup could reach 130°, radiate into the building, and cause the roof cover to deteriorate prematurely. Normal building moisture could also build up and greatly reduce the thermal effectiveness of the installed insulation, and, as a result, very minor roof leaks could cause some problems.
Moisture that leaks into the building or is generated within the building (i. e., interior plants, cooking, shower/bathroom, foundation moisture, etc.) migrates up through the ceiling in the form of water vapor. When roof framing spaces are not properly vented, moisture accumulates, hits the cold roof underside and condenses back to water. This water normally accumulates in the insulation and causes it to deteriorate.
Then, after a certain point, the water drips back down through the ceiling and out the roof edge. It is important to improve the building venting to keep interior moisture to a minimum. In spot checking, I observed no indications of significant problems with roof framing deterioration, but it is important that all existing roof layers be removed at re-roofing so the roof framing can be checked. Based on my observations, the cost to correct any roof framing damage that may be found should be incidental to the cost of re-roofing.
When roofs are not properly vented, a roof ice dam may form during freezing weather. Since air temperature in the roof framing space is not balanced, ice develops along its bottom edges when snow starts to melt. This creates a dam that causes water runoff to back up underneath roof cover joints and leak down into the building. Ice dams can usually be avoided if proper venting provisions are installed in the roof framing space.
One of the fundamental problems is that roof venting installers used the "1 per 300" rule, which is not appropriate for asphalt shingle roofs. Minimum code stipulates a net venting of 1 square foot per 150 square feet of horizontal roof surface. If 50% of this is installed at the upper half and the other 50% at the lower half, the amount of venting can be reduced to 1 square foot per 300 square feet of horizontal roof surface.
When asphalt composition shingles are installed, manufacturer's instructions and code normally require a minimum of 1 square foot per 150 square feet of horizontal roof surface. Minimum code is minimal (D) quality, and we have found that the amount of venting required by code plus 50% produces a very good quality system (we advise the upgrade). A roofer/vent installer needs to measure the building, do vent calculations, determine the type of vents to used to comply with minimum code requirements, and install them. If desired, venting can go beyond minimum code requirements (i. e., 1.5 times for very good quality).
There are numerous types of vent piece installations and custom screen type vents. Net ventilation amounts are stamped on standard vent pieces. The net venting of screening typically is 70% of the gross screened vent area. Ridge vents typically provide. 125 net square feet per linear foot, and roof jack vents (small box vents that go on roof surfaces) typically provide. 4 square feet each. Typically, 2-inch continuous screen venting provides. 1 square feet net venting.
We feel very positive about ridge vents because they are very easy to install, and they provide very effective venting. It is better to have roof overhang eave screened venting, but this is a little more difficult and costly to do, and it may not be practical (however, it would still be a good idea to obtain an eave screened venting estimate from a contractor). Visually, roof jacks are questionable, so it is best to install them on the back side of the building.
In spot checking I observed some areas where insulation clearance does not appear to have been installed properly. Current code requires a 1" minimum clearance between roof sheathing boards and the insulation layer (for proper through ventilation) and a 1" minimum clearance between roof sheathing boards and the through-vent area, where there may be framing blocking. It is important to check for adequate clearance during the next re-roofing, when insulation is upgraded and/or the existing roof cover is removed. There are other issues, but these are the main ones.