Discussions

To clear some issues up. The south side of my roof is clean and has no snow or ice. The north side is covered with ice from the rain we had earlier this week. But hardly any snow.  
 
My thumps in the house are only heard on the north side of the building and nothing on the south side.  
 
What about others???

It sounds like someone banging on the outside of my house. It seems to always be around the same time at night and early morning. Kind of creepy

We have only had the two big thumps, and both of ours seemed to be on the north side of our roof.

The sound you are hearing is the expansion or contraction of the bottom cord of your trusses. The bottom cord is warm and the top cords are cold, so they move at different rates. The noise will be the bottom cord rubbing against the top plates of your interior walls, with all the weight of the snow, there is a lot of pressure and when in moves, that is when the pop happens. Very seldom if ever, you should not hear this in older houses with stick framed roofs as the top cords and ceiling joists are not connected, and you will not hear this popping sound in the summer.

So should we just sit back and wait for it to stop? Is it going stop once it warms up a bit?  
 
Why does one of the popping sounds, sound like something is being dropped in the attic?  
 
I love this post by the way. Feel like I can quit worrying now.  
 
Edited by barrylincoln, 2017-03-10 22:31:58

I had 3 of these later last after I got home. I described it like it sounded like a very large ball peen or sledge hammer slammed the side of our stucco house. A couple smaller ones tonight not near as loud.  
 
Thank you for clearing this up for Me. I suspected ice build up but still was a little freaked out. Hahaha

Quite a few years back we heard loud intermittent BOOMS outside, like a big gun/cannon being fired. It made me uneasy, as there should have been no type of gunfire (and certainly no cannons) anywhere around us that day.  
 
It ended up being attributed to the nature/quality of the ice on the snow in the field at the time as it cracked & settled. That was also after a freezing rain.  
 
Maybe listen for that if you are out in the country. It was fascinating. I have only ever heard it that one day. Maybe this could be a year for a repeat?

North part of our house as well.

Sit back and relax, it will stop once it warms up a bit. Keep in mind that the pressure of the bottom cord of the truss on the top plate of your wall is tremendous and the bottom cord moves a millimetre or less it will make that popping sound. All is good

Frost quakes are caused by excessive moisture in the soil and sudden changes in temperature which we have experienced. They sound like a thud on the roof, which we started hearing yesterday. Our house has only a crawl space and is in very sandy soil. Also ice on the roof and gutters frozen.

This loud popping happened three times the other night and scared the crap out of me! I sent my husband outside with our baseball bat because I thought someone was trying to break in lol.

It is thermal bridging and thermal warp in the roof that happens with differences in outside air temperature meeting the ambient inside air. Causing expansion and contraction of building materials. I.e. trusses that are softwood lumber expanding and contracting. or steel nails and truss plates. Most thermal bridging happens at the truss to wall connection at the soffits because those are often the areas of least insulation. Yes changes in exterior temperature have something to do with it but minimal because our attics in a truss roof are to have the same temperature as the exterior air. They are vented to the exterior. They are not to be warm spaces. The snow build-up hypothesis is the extreme. We did have heavy snow this week. But if a roof is designed using newer building code guidelines it will carry nearly 40 pounds per square foot of snow load in our region. Couple that with our safety factors in our building code and you could park a volkswagen beetle on your roof and it would not fall through. older homes not so much. Don't worry about the pops they will go away as soon as the outside air temperature rises and meets your ambient house temperature. If you want them to be minimized and want to spend some money. Call a professional to check your insulation levels in the attic space. Top them up well over the truss bottom chords. Install insulation stops/air baffles at the eaves where the truss connects to the walls and then fill the truss heel with insulation. Keep as much warm air from escaping into the attic as possible. My 50 year old house actually has warm spots on the roof because of this. I can see them from outside. And it pops like popcorn all winter long!!!

My house has been doing this all winter on and off. Is there anyway to fix this problem in the future. Like better insulation in my attic. Or cutting in roof vents. Any thing I can do this summer to help next winter

Let's do the math here.  
 
Let's assume that the area of contact for the average Volkswagen on that roof would be about 1sqft per tire (pretty liberal there). And that the car weighs no more that 1,000lbs...pretty conservative there  
 
Anyway, that would far exceed the limit of 40 lbs/sqft....no? (roughly 250 lbs/sq ft. by my math, on a very conservative estimate)  
 
You'r roof is designed to support an evenly distributed load, NOT point loads.  
 
Please do not attempt to park a small car on your roof, people!!!

this is Dan Forsythe Structural Designer.  
I was not suggesting people start building ramps and make parking pads of their residential roof structures.  
It was merely to make a point that unless the snow on the roof was severely drifted it was not going to cause a catastrophic failure of the roof system in a newer home.  
 
Also your math is simplistic. I have spent 18 years designing structures of all kinds and a lot goes into designing roof structures for snow and dead load. Mind you softwares today take care of much of the calculation for designers! Limit states design factors loads up. It factors member capacities down. There is load sharing for adjacent members. There are several different load cases in designing roof structures. One of those is a point load case. Drifting snow is also considered at any low to high roof intersections.  
 
No need to have a competition to see who is smarter!  
It is not an ego contest.  
I was just trying to make my point.  
 
Cheers.

Shucks, I''ve already started building my ramp.  
Dan, I just had to say that, thanks for your comments.  
 
Edited by don brown, 2017-03-15 21:43:48