How to Inspect Your Own House, Part 3: Siding

This is part three in a multi-part series of How to Inspect Your Own House. In part one, I covered how to inspect your own roof and chimney. In part two, I covered the inspection of the exterior water management, which is one of the most critical parts of preventing major water damage to a building. Today the focus will be on inspecting your own siding, broken down by the most popular types of siding in the Twin Cities. Oh, and a note to any word sticklers: a more technical / accurate term for siding would be "exterior wall covering", but that term is a little geeky and pretentious. I'm happy to call the stuff that covers the exterior walls "siding", whether it be vinyl, stucco, wood, etc.

The two most common problems you'll find with wood siding and trim are peeling paint and rotted wood.

Peeling paint is an obvious defect that can be spotted from a block away. Paint is meant to protect wood surfaces from decay and rot, but it's not common to find rotted wood siding because of lack of paint. The main issues with peeling paint at siding are that it looks horrible, it's an environmental hazard if the paint contains lead, and it may violate a maintenance code for the city. For example, section 244.500 (d) of the Minneapolis Housing Maintenance Code says "No exterior wall of any dwelling or building accessory thereto shall have paint which is blistered, cracked, flaked, scaled, or chalked away." I don't have any inside tips to share on peeling paint; if you need more info on that topic, check out what Dr. Lstiburek has to say about it.

Rotted wood siding isn't much of an issue at old houses in Minneapolis and Saint Paul that have been sided with old-growth wood; it's more of a 'new wood siding' type of issue. To inspect your own home for rotted wood siding, start by figuring out which areas will be prone to rotting first. If you've already taken the advice that I gave in last weeks blog post about exterior water management, you'll probably have a good idea of which areas you need to pay the most attention to. Areas of the house that are covered by big soffits / overhangs will probably be fine.

The areas that turn into problems are the areas where water gets concentrated.

Other areas to pay special attention to are the siding below roof ends with missing kickout flashing, below bay windows, and at wood chimney chases. Also, any areas that have water splashing against them will be prone to rotting. To check for rotting at wood siding, start by looking for obvious things like holes in the siding. Be sure to look at everything. As shown in the photo below, this might require walking the roof.

The next step is to go around and poke at the areas that will be most susceptible to water intrusion and rotting. You can sometimes just push on the siding with your fingers to find rotted / soft areas.

Look for areas with missing or dried out caulking that need attention. If rotted siding is found in several areas, there's a good chance that there's rotted wall sheathing behind the siding. There are two ways to check for rotted wall sheathing; remove the siding and check it out, or have moisture testing performed on the home by a company that specializes in this. When we conduct moisture testing on wood siding, we start by scanning the siding with a non-invasive moisture meter. Areas with elevated moisture levels are tested the same way that stucco siding is tested; two small 3/16" holes are drilled, and a moisture probe is pushed into the wall to determine the moisture content and condition of the wall sheathing.

First, a quick primer on vinyl siding. Love Tolerate it or hate it, vinyl siding is very good at what it does. Vinyl siding is an exterior cladding that reduces the amount of rain that reaches the stuff underneath it, which is referred to properly as a water-resistive barrier, but more commonly as Tyvek®, which is a brand name. Vinyl siding is not watertight and isn't designed to be watertight. Vinyl siding should always be installed over a water-resistive barrier, but this wasn't required by code in Minnesota until 2003. If you have a home built before 2003, you may or may not have a water-resistive barrier behind the siding. After 2003, it should definitely be there.

The most common visible problem with vinyl siding is physical damage from hail, basketballs, baseballs, weed trimmers, or rocks thrown from lawnmowers or snowblowers. Small chips and nicks aren't big performance issues; remember, vinyl siding is not watertight. The main issue with physical damage to vinyl siding is that it makes the house look bruised up. The photo below shows an extreme example of a house with some nasty hail damage, as well as some makeshift repairs by someone with a short ladder and a long roll of tape. This siding is clearly in need of replacement.

Vinyl siding can also melt / deform when someone has a grill too close to the siding, or from reflected sunlight on low-e windows. The photo below shows an example of deformed siding caused by reflected sunlight. This is a cosmetic issue; the vinyl will still do its job even though it looks terrible.

Unfortunately, homes with vinyl siding can experience water intrusion just like homes with other types of siding. There is typically no visible evidence of moisture intrusion with vinyl siding... at least not until it's too late. The nice thing about vinyl siding is that it's fairly easy to pull apart and put back together without any tools. The video below shows me pulling apart vinyl siding on a bank-owned property that had experienced major water intrusion. As you can see, it's pretty easy to open vinyl siding up.

Old stucco houses typically don't have big problems, while newer stucco homes (late 80's +) often do. There's not much that can be seen to identify major problems with stucco houses. Stains below windows and other similar penetrations in the walls are cause for concern, but they're not necessarily a problem.

As I've said for many years, long before we ever began doing moisture testing on stucco houses ourselves, the only way to know for sure is to have invasive moisture testing performed.

Stone siding is typically installed only on the front of houses, but it's subject to the same problems as stucco, and problems with moisture intrusion are just as difficult to identify. It requires invasive moisture testing. For info on stone siding installation defects, click here: http://www.structuretech1.com/2012/09/stone-siding-installation-defects/

Hardboard siding, often called masonite, is a pressed wood siding product that lasts about 20 - 30 years. When hardboard siding rots, it's usually quite easy to spot, as it really starts to look nasty.

Hardboard siding typically fails at the lowest courses first, usually from water splashing up against siding that has been installed too close to the ground. When it's just a few pieces of hardboard siding that are rotted, the appropriate repair is to replace the rotted pieces of siding. Once there is rotted siding in many areas throughout the exterior, it's time to reside. I have more examples of rotted hardboard siding at the end of this post: http://www.structuretech1.com/2013/04/home-inspection-checklist-exterior/

The most common problems I find with these types of siding are improper nailing and improper clearances to grade, hard surfaces, and roof coverings.

My best advice for inspecting these types of siding would be to read the installation instructions from the manufacturer, then walk around your home and make sure the installation details match up with the diagrams the manufacturer provided. I have installation instructions for James Hardie siding going back to 1998 on one of my older blog posts about that product: http://www.structuretech1.com/2009/08/problems-with-james-hardie-siding-installations/ .

While this is obviously not a full list of siding products used in the Twin Cities, these are definitely the most common. Same goes for the list of problems. Next week I'll have a blog post on inspecting the rest of the exterior of your home.

Author: Reuben Saltzman, Structure Tech Home Inspections