Rammed Earth In Quebec!
Terra Sol's Mike Wilson sends us this field report:
I went to Hudson, Quebec as a Rammed Earth consultant for the first insulated rammed earth house in Quebec. I was present for the first half of the rammed earth portion of the project, to get the crew up and running.
M.A. Construction, a company intent on building environmentally-friendly, energy-efficient houses in the Montreal area, will finish the remaining rammed earth walls and the rest of the house.
The home-owners gave the architect a mandate to 'build the greenest house you can imagine'. The owners are exceptional people and obviously committed to doing something progressive with their project.
The house has been designed to capitalize on the solar exposure of the site. The building envelope is a combination of insulated rammed earth, wood framing and insulated bermed concrete. The rammed earth interior walls are the main load bearing structure for the roof, which incorporates a clerestory window running the entire length of the house. This brings light into the house and passive solar heat to the walls.
The exterior walls have detailing at the foundation to deal with the extremes of heat, cold and humidity that is characteristic of the local climate, and to ensure that moisture will not get trapped inside the wall and freeze. There was a percentage of pozzolan used in the foundation concrete which allowed the cement content of the foundation to be cut by about 25%. It also meant that the foundation formwork had to be left on for several days instead of being stripped the day after pouring. The exterior walls are also load-bearing.
The puddled earth cap for the exterior walls are separate for each wythe so that the insulation can be continuous into the roof instead of having any uninsulated bridges into the house. The Montreal area is classified as seismic zone four, so the rebar is on a sixteen inch grid with rebar crosses to tie the two wythes of the exterior walls together.
The building soil was trucked in from a few kilometers away. Compression tests came in at 13-14 Mpa with 5% cement. We were also using Xypex c1000 to increase the moisture resistance of the walls. The c 1000 is neutral for cure time because we didn’t need to worry about extending cure time due to the cool temperatures and high humidity. In fact we were adding hardly any water to the soil which sometimes made it difficult to mix in the colour really well. The walls are very dark, a deep brown colour that the homeowners requested.
The end panels for the rammed earth forming system were built using 2x4 and the same paper faced MDO form-ply used for the rest of the formwork. There were no chamfers in the end panels because the homeowners wanted clean, solid 90 degree corners at the ends of the walls. The corners came out out of the forms looking great. "Corner protectors" were constructed to protect the corners for the duration of the building process .
2x10 walers and 2x12 microlams were employed as strongbacks. Forms were built for three walls, partly so that we could leave the formwork on the wall for a few days to get some extra cure time and insulation before stripping.
The formwork went up pretty well apart from the fact that the foundation people hadn’t done a great job making everything straight and level. So we attached ledgers to the stem walls and snapped lines on them so that we could sit the main panels straight and level. Also the interior walls were pretty high….. 12’6 – 14’ off the footing which meant a bunch of associated extra time, expense and logistics. Just getting the formwork up that much higher is quite a bit of extra work as well as having to have the telehandler or ‘zoom boom’ to get the soil up there because the bobcat didn’t reach. The end panels were so tall, to get the braces and strong backs on them required the use of a very high step ladder. Building the end panels with garden variety 16’ 2x4s meant that they weren’t perfectly straight and so we had to plumb things up as we progressed with ramming.
That said, the walls came out really plumb and square, no more than ¼” out over 12’6” but usually they were perfect. Pretty impressive what you can do with what some people like to condescendingly label ‘agricultural formwork’. One other thing that made the building a little complicated was that the interior walls at one end of the house were very tightly packed, which made building subsequent walls a bit trickier. Other than that, the ramming went well. The sheer size of the walls meant that even with four rammers working, the days were long. Martin of MA construction didn’t want any cold joints, so we pushed the ramming crew, sometimes well past dark. There was only one cold joint at the top of the first wall, and I think due to the cool temperature and humidity, when we stripped the formwork, no one could tell that we had stopped at all at that level.
Generally everything went well, the weather has co-operated so far. The walls arecuring perfectly , completely dry after a few days out of the forms. As long as the real cold doesn’t hit until at least a few days after the last wall is rammed, they should be able to cover the walls and continue getting the rest of the house and roof up.
It was a pleasure to work with those guys, everyone involved worked really hard and with good humour. They were all really interested with the rammed earth, the motivation of the project and green building in general. I can't wait to see the place when it is finished.
I went to Hudson, Quebec as a Rammed Earth consultant for the first insulated rammed earth house in Quebec. I was present for the first half of the rammed earth portion of the project, to get the crew up and running.
M.A. Construction, a company intent on building environmentally-friendly, energy-efficient houses in the Montreal area, will finish the remaining rammed earth walls and the rest of the house.
The home-owners gave the architect a mandate to 'build the greenest house you can imagine'. The owners are exceptional people and obviously committed to doing something progressive with their project.
The house has been designed to capitalize on the solar exposure of the site. The building envelope is a combination of insulated rammed earth, wood framing and insulated bermed concrete. The rammed earth interior walls are the main load bearing structure for the roof, which incorporates a clerestory window running the entire length of the house. This brings light into the house and passive solar heat to the walls.
The exterior walls have detailing at the foundation to deal with the extremes of heat, cold and humidity that is characteristic of the local climate, and to ensure that moisture will not get trapped inside the wall and freeze. There was a percentage of pozzolan used in the foundation concrete which allowed the cement content of the foundation to be cut by about 25%. It also meant that the foundation formwork had to be left on for several days instead of being stripped the day after pouring. The exterior walls are also load-bearing.
The puddled earth cap for the exterior walls are separate for each wythe so that the insulation can be continuous into the roof instead of having any uninsulated bridges into the house. The Montreal area is classified as seismic zone four, so the rebar is on a sixteen inch grid with rebar crosses to tie the two wythes of the exterior walls together.
The building soil was trucked in from a few kilometers away. Compression tests came in at 13-14 Mpa with 5% cement. We were also using Xypex c1000 to increase the moisture resistance of the walls. The c 1000 is neutral for cure time because we didn’t need to worry about extending cure time due to the cool temperatures and high humidity. In fact we were adding hardly any water to the soil which sometimes made it difficult to mix in the colour really well. The walls are very dark, a deep brown colour that the homeowners requested.
The end panels for the rammed earth forming system were built using 2x4 and the same paper faced MDO form-ply used for the rest of the formwork. There were no chamfers in the end panels because the homeowners wanted clean, solid 90 degree corners at the ends of the walls. The corners came out out of the forms looking great. "Corner protectors" were constructed to protect the corners for the duration of the building process .
2x10 walers and 2x12 microlams were employed as strongbacks. Forms were built for three walls, partly so that we could leave the formwork on the wall for a few days to get some extra cure time and insulation before stripping.
The formwork went up pretty well apart from the fact that the foundation people hadn’t done a great job making everything straight and level. So we attached ledgers to the stem walls and snapped lines on them so that we could sit the main panels straight and level. Also the interior walls were pretty high….. 12’6 – 14’ off the footing which meant a bunch of associated extra time, expense and logistics. Just getting the formwork up that much higher is quite a bit of extra work as well as having to have the telehandler or ‘zoom boom’ to get the soil up there because the bobcat didn’t reach. The end panels were so tall, to get the braces and strong backs on them required the use of a very high step ladder. Building the end panels with garden variety 16’ 2x4s meant that they weren’t perfectly straight and so we had to plumb things up as we progressed with ramming.
That said, the walls came out really plumb and square, no more than ¼” out over 12’6” but usually they were perfect. Pretty impressive what you can do with what some people like to condescendingly label ‘agricultural formwork’. One other thing that made the building a little complicated was that the interior walls at one end of the house were very tightly packed, which made building subsequent walls a bit trickier. Other than that, the ramming went well. The sheer size of the walls meant that even with four rammers working, the days were long. Martin of MA construction didn’t want any cold joints, so we pushed the ramming crew, sometimes well past dark. There was only one cold joint at the top of the first wall, and I think due to the cool temperature and humidity, when we stripped the formwork, no one could tell that we had stopped at all at that level.
Generally everything went well, the weather has co-operated so far. The walls arecuring perfectly , completely dry after a few days out of the forms. As long as the real cold doesn’t hit until at least a few days after the last wall is rammed, they should be able to cover the walls and continue getting the rest of the house and roof up.
It was a pleasure to work with those guys, everyone involved worked really hard and with good humour. They were all really interested with the rammed earth, the motivation of the project and green building in general. I can't wait to see the place when it is finished.
posted by Rammed Earth at 6:21 PM
2 Comments:
Really amazing stuff. Can you comment more generally on your experiences with rammed earth in Quebec? Is the soil typically suitable for rammed earth? What else needs to be added? Also, what is a "cold joint"?
To find out more about the rammed earth experience in Quebec, give the good people at Terra-sol a shout!
http://www.terra-sol.ca/
Typically cement is added to soil.
A cold joint is the 'joint' between two different layers done on different days. In the time elapse, the lower layer shrinks. The layer on top is of a different size--just big enough to interrupt the 'plane' of the wall.
Did that make sense?
Thank you for writing!
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