Home & Garden Columns

About the House: Ask Matt: Addressing House Foundations, Shingle Roofs

By Matt Cantor
Friday November 10, 2006

Dear Matt, 

I read your article about house foundations, and I was wondering how do I tell if my house is bolted to the foundation. I live in the Seattle area, and my house was built in 1972, so I’m pretty sure that it is bolted, but I’ve torn apart a few small drywall piece, and haven’t seen any bolts. Is there an easy way to tell?  

I’m asking because I am looking at getting earthquake insurance, and it is one of the requirements.  



Dear Tom, 

This is a toughie as there are a number of questions you have to ask yourself to get a clear answer. The first one is, Do you have a crawl space? If there is a space between your floor and the ground then your removal of drywall isn’t going to tell you what you need to know. If you’re on a slab, where the foundation and your floor is the same thing, then it will. If you are on a slab, and there are plenty of those from the 70’s, you will probably have to remove drywall along the floor for up to 6’ before you see a bolt and possibly further. Bolt spacing in this time was roughly at a 6’ spacing and the bolts are usually 1/2” with small washers (if there ARE washers). The nuts may be square or hex and these are likely to be quite rusty since they were almost always non galvanized. Your insurance company probably doesn’t care how many bolts are present, just so long as some can be sighted.  

If you have a crawl space, you will notice that your floor is a) usually raised above ground level any where from 2’ on up and you’ll usually have to walk up some stairs to get into the house from at least one side. If you have a crawl space, you’ll also usually see vent on the side of the building just above ground level. If you have a crawl space, you will also, generally, be able to hear a drum-like sound when you jump up and land on the floor. A slab won’t make any sound beyond the sound of loose flooring. It will also feel very hard and unforgiving.  

If you have a crawl space, you’ll need to get inside of it to see the bolts and they will be on the top of the foundation around the perimeter of the building. They hold the bottom piece of wood that makes up the framework of the house, called a mudsill, to the foundation. This board literally lies flat on top of the footing and is held in place by an occasional bolt. Since bolting was a requirement in virtually all of the U.S. at that time, you can expect to see a small compliment of 1/2” bolts just as I’ve described above. Keep in mind that with a slabbed house, you’re only going to be able to see a sampling. Bolting frequency may vary and the spot you see won’t tell the entire picture. That said, it’s a good idea to find out for your insurance company and for yourself. I hope you’ll consider upgrading the bolting since almost all of the bolting done this long ago, is now considered to be far too weak and Seattle is much like Berkeley in its seismic activity.  

Say hi to Bill and Melinda for me,  



Dear Matt:  

I have a 15 year old composite shingle roof. About five years ago I noticed that all the mineral granules on the ridge shingles were gone. The ridge shingles are two or three shingles thick to give a perky profile. Another roofer doing my garage said the problem is the shingles on the ridge get too hot because the heat in the unventilated attic crawl space is hottest at the ridge. 

Does this make sense to you? the flat shingles that start at the edge of the ridge shingles, just a few inches down from the apex of the ridge look fine.  

Sam Craig  


Dear Sam, 

That roofer of yours is a pretty sharp fellow and there’s a darned good chance that a lack of roof venting is involved in the wear on those shingles, however, I’m going to ask you to take a closer look at the shingles to see if there’s something else going on, perhaps in addition to the problem with heat and very possibly the root cause of the problem. I’ve seen a similar condition on quite a few occasions. You may be looking at a problem that occurred as a result of folding the shingles. When shingle get folded over the ridge they tend to more rapidly shed their mineral coating. Some roof ridges, such as the one you’ve described even involve a complex fold in which the shingle is folded in half and THEN folded partially once again to bend over the ridge.  

This creates a more elaborate ridge detail that sort of puffs up like a bird’s crest. It’s pretty but it involves paying a price. This folding immediately knocks some mineral granules off and then promotes more failure of the mineral coating over time. If the mineral is only missing (to a significant degree) on the ridge shingles and the adjacent ones, which lie flat, seem completely fine, I’ll bet that the folding is the primary problem. If heat is the problem, I would expect the top 2-5 courses to have a graduated effect in which the top is most strongly effected and the next few courses have a decreasing but noticeable loss of the granules. Heat in the attic, if this involved, will also tend to curl the shingles and I’ve seen cases where all the shingles had some lift to them as the heat waves were driving them upward. The shingles also become quite brittle in these cases and begin to crack and break prematurely.  

If it’s just the ridge shingles that are badly worn and the rest looks all right, I’d suggest replacing the ridge shingles with new ones. It’s not hard to get a similar color. At 15 years, you may only have a few years left on the whole roof so consider this when you think about putting money into a repair. I DO think that roof heat is an issue that should be addressed during the next roof replacement by the installation of vents (they can go in several places and are best distributed somewhat over the height of the roof (some near the top and some near the bottom). You can also consider a fan (and solar fans are nice in that they don’t require any wiring).  

Good luck, Matt  


Got a question about home repairs and inspections? Send them to Matt Cantor at mgcantor@pacbell.net.