Help Please - Insulating Options Under A Driveway?

[Sawyer]

I am going to be running my supply lines under my driveway for 80’. I was told that it may be best to place a 2’ wide 2” thick sheet of foam over the pipe after is sprayed with the closed cell foam. I am wondering if I would not be better off to have the insulator apply more foam around the pipe in those areas rather than cover with the foam board. Does anyone out there have any experience with either type of installation?

Thanks, George

 

[Sawyer]

Does anyone out there have any experience with either type of installation? I have to have my trench ready for the insulator on Thursday and I do not know which method would be the best. I want to do this the best way possible the first time.

George

 

[don f]

How deep of a trench are you going to dig . The deeper you go the less chance of frost getting to it.Mine is 6' deep spray foamed in layers 12" thick. I did not follow my driveway
Good luck. Don

 

[Sawyer]

How deep of a trench are you going to dig . The deeper you go the less chance of frost getting to it.Mine is 6' deep spray foamed in layers 12" thick. I did not follow my driveway
Good luck. Don

Mine will be about 6’ deep also Don, unfortunately I cannot avoid the driveway. My pipe has to run under 80’ of driveway and enter through the mechanical room wall under the front steps of the house. It is all sand so I am not sure how deep the frost goes but considering we are up by Lake Superior and it is plowed all winter I am sure it goes deeper than 6’. I could go under a shorter length of driveway if I ran the pipe up the outside of the house in an insulated chase and then through the floor joists to the mechanical room ceiling but I was worried about the pipe on the outside wall. Rethinking the plan I may be better off with 20’ of driveway and in an insulated chase than the previous plan. I could insulate the pipe in the chase with sprayed foam in the chase. Thanks for getting me thinking again Don!

George

 

[rjkohrs]

I'm new to this group, but not to wood burning. Find a place that recaps tires and get some rubber dust (shavings) from them. Some of the best underground piping insulation there is, and most places are happy to give it away.

 

[leaddog]

I am going to be running my supply lines under my driveway for 80’. I was told that it may be best to place a 2’ wide 2” thick sheet of foam over the pipe after is sprayed with the closed cell foam. I am wondering if I would not be better off to have the insulator apply more foam around the pipe in those areas rather than cover with the foam board. Does anyone out there have any experience with either type of installation?

Thanks, George

I would think that if you sprayfoam with atleast 3in of foam and then lay 2in of sheet insulation you would be fine. You will have heat going thru the pipe all winter so freezing isn't a problem and if you are 6ft deep driving on it won't crush it. Some people have run there insulated pipe on top of the ground and not had a problem.
leaddog

 

[Sawyer]

I'm new to this group, but not to wood burning. Find a place that recaps tires and get some rubber dust (shavings) from them. Some of the best underground piping insulation there is, and most places are happy to give it away.

We do not have any tire shops near, thanks for the suggestion!

 

[Sawyer]

I am going to be running my supply lines under my driveway for 80’. I was told that it may be best to place a 2’ wide 2” thick sheet of foam over the pipe after is sprayed with the closed cell foam. I am wondering if I would not be better off to have the insulator apply more foam around the pipe in those areas rather than cover with the foam board. Does anyone out there have any experience with either type of installation?

Thanks, George

I would think that if you sprayfoam with atleast 3in of foam and then lay 2in of sheet insulation you would be fine. You will have heat going thru the pipe all winter so freezing isn't a problem and if you are 6ft deep driving on it won't crush it. Some people have run there insulated pipe on top of the ground and not had a problem.
leaddog

Leaddog, I guess the foamboard will be cheap insurance. I worry about above ground when i read experiences of green grass paths in the snow above various insulated pipes that are burried. Maybe I worry too much as we are using closed cell foam. Thanks for your comments, George

 

[heaterman]

This is how we do drives but it may not be feasible for your application seeing that you are running such a distance. It would be a lot of work. We have had excellent results with this and we never go more than 3' deep.

We cut 2" foam board and lay it on the bottom of the trench then place the tube and spray it. The spray will bond right to the foamboard. The next step is to cut 12" strips of foam and place it vertically on the bottom piece in the trench so as to build the sides of a box. We then fill the box with sand, compact level with the top of the 12" sides and place a "lid" of foamboard on top. The foam box is then backfilled carefully with more sand to about 6" over the top of our box and compacted again. Then we back fill to grade level.

We have never seen any trace of thawing or settling on any of the drives we have done in this manner and we have a couple that see very heavy ag traffic over them daily. I'm talking about loads of 80,000#'s + every day. Even at a depth of only 3' the water in the tubes would have to be stagnate for days before it froze due to the thermal mass of the sand inside the box.

 

[Sawyer]

I like your design Heaterman, if I can get more 2" in time I will follow your design. We are in an all sand area so I laready have the right fill. I do want this system to be trouble free. Thanks to your help and the help of others it has a good chance.

Thanks, George