Most of you probably slept right through it (the quake), Yes – we usually do.

Most of you probably slept right through it (the quake), Yes – we usually do.

That’s right, we usually do, or other wise not notice because we’re driving or otherwise in motion. Yeah, I’m talking about last night’s earthquake.

 http://www.cbc.ca/news/canada/montreal/story/2012/10/10/montreal-longueuil-quebec-earthquake.html

 I’m usually one of those who ‘miss’ it but last night was the exception. I experienced a 10 second pulse of shaking that left no doubt as to what it was.

Some people heard a bang and some experienced just shaking. If you or your property is on rocky ground or bedrock you’d have heard the bang more. If your house sits on clay you’d have been shaken longer and heard less noise. Those on higher floors do sometimes feel more motion, depending on the type of structure.

 As a Montreal home and property inspector I have to tell you that whether or not you noticed it, your house surely did. You may have some wall or basement cracks appear, existing cracks open and close, or there may be no noticeable effects at all.

 I often get asked if basement cracks are structural and what the cause might be. Same thing for wall cracks in 1950s built homes.

Last night we experienced a rare occurrence (thankfully) that does cause this type of cracking.

 If you have a crack in concrete or masonry that has opened more than a pencil thickness, or has one side moved (in-out, up-down) compared to the other side then you should have it evaluated by a professional like me.

 1950s built homes with plaster-gypsum lath walls are rigid and inflexible. They crack easily. Hairline cracking is common.

 But if your walls are joint taped gyproc (i.e. drywall) and you have a new crack after last nights quake then that is more significant because this system already allows some movement.

Call or email me if you have any doubt or concerns.

 

Robert Butler 514 914 1249, robert.butler@aspectinspection.com

 

N.B.   The quake occurred in the fault line (system) that is responsible for the straight north south axis of the Richelieu River.  Most major rivers have such fault lines associated with them.

 

Original blog post on ActiveRain: Link to Blog Post

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“Faulty Towers”…..Funny, Faulty Decks………Dangerous !

“Faulty Towers”…..Funny,       Faulty Decks………Dangerous !

Faulty Towers was a hilarious British comedy. it was a sit-com staring one of the founding members of ‘Monty Pythons Flying Circus’.

Faulty decks though that’s a different kind of story, and if you are unlucky it’s appearing on a balcony or deck near you.

Take a look at the example below and remember just because it’s been there for a while doesn’t mean that it always will be (there).

deck defects

At ‘A” you can see the short remnant of the original cantilevered beam built into the original floor framing of this building.  The joists of the current construction are sistered onto either side. This is nailed with 4″ common nails, not galvanized.

B” Is the top end of the diagonal brace, a 4 by 4 bracketed by the sistered joists mentioned above. The same type of nails are used, but smaller ones.

C” the base of the same diagonal brace is set into a shallow pocket in the cement bonded stone foundation wall. There is a horizontal steel pin, basically a spike nail pining it from moving.

So whats wrong with that you say?

Well: Nails are just pins that lock things in place . The weight transfer has to be wood resting on wood.

Nailing wood the side of another wood member without notching it in to support it from underneath means the weight transfer is being done on the nails. Nails can not resist the stress over time.

They seem to work when everything is new and tight. Then things get a bit loose and flexible. For a while there is a little ‘wow’ deflection felt. It can last for years. You’ll even forget about it. “Oh, it’s OK, it’s aways been like that”.

The nails loosen from wood shrinkage, wood degrades from water exposure and nails rust, loose diameter and loose their hold strength.

Then one day it’s not OK. Gravity wins, you loose.

At ‘C‘ water collects here, keeping the wood wet, slowly rotting and the spike nail rusting.

To be safe:

A and B have to be bolted though with non rusting blots that pass through all the wood members and clamp them together. The number an spacing have to be staggered to prevent check splitting down the length of the grain.

C needs a rust proof bracket that holds the wood brace end off the stone to allow it to dry after rains and holds it securely on the stone foundation with through bolts. Lag bolting and cinch anchor bolts cannot be guaranteed to work on all kinds of stone.

Now look around the corner to this part of the structure:

ledger defects

Here we see some of the more common problems with decks.

The ledger board (against the wall), has no flashing and only has two (E) lag bolts set in mortar.

Now look at where the joists join onto the ledger (D). You can’t see the nails because they are very small. There’s only 5 of them and they are not galvanized.

To be safe; The ledger board has to be solidly attached. That means at least 5 bolts in this much space.

Ideally the bolts should be through bolts but if the stone is too friable then shorter lag or cinch anchor bolts can be used provided they are doweled into the stonework with epoxy. Of course they have to be galvanized or made of non-rusting alloys.

I’ve seen some amateur use of tapcons here (cement or masonry anchoring screws). They should never be used – they have even less shear strength than nails. They fail by just breaking off. The metal is not strong enough.

The ledger has to be flashed to keep it dry or wood rot decay will be a problem. Don’t count on pressure treated wood to be sufficient. Remember you are not building for the weekend or just the next ten years, you’re building for forever.

Lastly; Joist hangers – the proper type will not rust and each joist will be secured with 14 nails not not just 5 ‘toed’ nails.

DO NOT use screws at any structural joints including joist hangers or any other bracket that transfers weight. 

Fire code requires that all structural weight bearing or transferring joist brackets (and other similar hardware  attachments) be only attached with nails (not screws or ring shank nails).  This is for the safety of firemen so that when floors burn through, the joist and other horizontal timbers be allowed to release and fall without pulling down the walls on top of the firemen. Screws disrupt that release.

 

So if you’re looking at property anywhere in the Montreal area and you need a full inspection…………

 

Original blog post on ActiveRain: Link to Blog Post

“Up She Comes”, Regional Difference – Climate Factor

 

Climate difference does mean different construction details. A North Carolina inspector showed me the following diagram of foundation details. We were discussing differences and water problems that crawlspaces have.

The construction shown would not be built for Canadian climates but is OK for North Carolina which is a significantly different climate. The discussion describes what happens in Canadian soils and the different details that mitigate the conditions.

 

foundation drwg

Yes, It’s a regional difference because there is a climate difference.

This set up (shown in the diagram) will let water soak into the brick and concrete. When it freezes here (frost depth; down to 4′ below the surface – on average) the water expands, cracks and breaks the concrete block and brick. That’s the freeze thaw cycle. This will destroy the wall a little more each time.

This happens all winter, a three or four-month period is normal. Today for example it was -14 C (Centigrade/Celsius 0= 32 Farenheight) this morning. This evening it was up to -3 C. Some house foundation walls, especially facing south will have gone through the freeze thaw cycle today. The temperature has swung up to melting and back down to hard freeze 3 to 4 times in the last 2 weeks.

Here brick HAS to stop at least 8″ above the ground level. Concrete or cement block then extend to a minimum of 4′ below grade, to the top of a 12 to 18″ deep concrete footing that MUST rest on undisturbed soil. That’s the minimum; it is usually 6 to 8′ deep. Shallow is more susceptible to freezing effects. Remember the 4′ frost depth quoted is an average. There will be spots or conditions where it is deeper.

When water in the soil freezes it expands and puts pressure on its surroundings.. Downward and laterally the weight of other soil is infinite, pushing back. Upward its a different story, or two or three or more stories depending on the building. This resistance is not infinite so “up she comes”.

This is frost jacking. Frost has been known to lift 7 story structures. So you may have some idea what it can do to a mere house.

Frost heaving is the same thing but this term is more often used to describe landscape displacement.

The footing HAS to be concrete. The foundation wall can be concrete or cement block. BOTH require a waterproofing layer on the outside from ground level down to the bottom of the footing.

Current ‘best building practice’ now installs a drainage plane layer between the exterior waterproofed surface and the ground. This is to let any water present descend. (If there is no water retained against the foundation wall, there will be no seeping or leaking to the interior) The water descends to the weeping tile or French drain at the lower edge of the footing.

This is a belowground landscape drainage system designed to remove all water that is collected. (If no water is allowed to remain in the footing area, no frost jacking can occur.

                           ————————————-

 You can see why my comment about the diagramed footing you showed me was “Water runs through it.”

 Crawlspaces and basements between those walls will be wet any time the ground is. They will actually be wetter than the outside ground because that ground is better vented, it doesn’t have a cap on it, the house.

It will be very hard to vent such a crawlspace and what water does get evaporated and removed is constantly replenished from the ground through those walls.

 

In a high humidity summer climate this basement / crawlspace is actually cooler, and condensation can occur. That’s why un-insulated basements are ‘cooler’ in the summer, (and musty smelling.)

 Hence, “Ventilation is futile”

                         ————————————-

 “If the last instalment on your grandmothers’ funeral isn’t paid, up she comes”

 

 

 

Original blog post on ActiveRain: Link to Blog Post