I wonder how these hold up in fires.
I’ve seen hay bales catch fire from being too wet, no way I’m building a house out of that.
Yeah, same as wood, who would build houses out of that? /s
Hay is great insulation and it’s sealed with protective material anyway in modern houses. Also, even if not: Some tribes make houses out of hay or straw and those houses are quite great in their particular circumstances. There are experiments to use hay bales for structural support as well and it holds up surprisingly well.
Also, fun fact: wooden houses are less dangerous in case of fire than houses made of steel and concrete because the steel rod reinforcements start becoming soft at low temperatures (~200°C) and crash. Wooden houses announce crashing when burning, concrete buildings don’t.
The moisture and organic material causes mold and bacteria to form and create heat. Because hay is a good insulator, heat will build up more and more. Once the hay gets to a certain temperature flammable gases are formed and can combust from the heat.
Straw is compressed in the walls, so not to let oxygen go through, and it doesn’t get wet as the wall is covered with clay inside and outside.
But the moisture content of the straw matters BEFORE it gets sealed. A stack of a thousand damp bales can heat and combust. And it’s the interior damp bales that heat and start the fire.
They can get wet waiting for transport to the jobsite, they can get wet during transportation, and they can get wet during building.
I’m not saying a strawbale house can’t be well built, but it’s not a “one size fits all” solution for every location.
So flammable mater + low airflow is somehow more fire resistant than flame resistant mater + low airflow? Looks like the source is pure marketing unless their comparable insulation is perforated cardboard coated in fuel gel.
Roof/attic often uses rockwool or glasswool. Wall insulation is often something like XPS, PIR or PUR.
Although it sounds counterintuitive, I can see straw doused in flame retardant being better than supposedly flame retardant polystyrene foam made from hydrocarbons. I mean, just look at what happened with Grenfell Tower.
From the article…
Since straw bales are tightly packed, they do not burn as easily as certain other materials. The tight packing reduces airflow, something that is critical to sustain a fire. While there is some fire risk during the construction phase (as is the case with many building materials), once the home is finished, it’s flame retardant nature decreases the risk, usually resulting in a home that better resists burning than a traditional stick built house.
“…better than a traditional stick built house”
I’m thinking of brick, what do we think folks? Seems like we have three possible building materials with one clear winner amirite?
I don’t see how brick is the “one clear winner”.
A straw and clay house is better insulated and you need no cement. It has pros and cons.
Well hemp bricks hold up well so I am guessing they improved upon this too to be more fire retardant
I built my own strawblae house and have worked on half a dozen others. I have designed 3 award winning homes, one of them was strawbale.
Mice aren’t a problem, the walls are sealed with clay (inside) and lime (outside) render, the mice can’t get in.
Same with fire, the straw is tight and sealed, they don’t burn. In huge bushfires in southern Australia a few years back, several families sheltered I a strawbale home as the fire passed.
Moisture not a problem if you have proper eaves and footings, which you will cos you design it properly, right?
Loads of massive benefits over brick or stick built.
I have no data on wolves sorry, but definitely dropbear proof
Happy to answer any questions.
My biggest question is: why?
If it’s safe from mice, bugs, and fire, then it just seems like the housing equivalent of wearing a boot on your head. You can do it. It’s not hurting you or anyone around you. But it’s kinda just weird. Is there some sort of benefits to this over a normal house? Or is it just a boot on your head?
Pros: Cheap, good insulator, doesn’t require any experience to install, local, low environmental footprint.
Cons: Thick, does not handle moisture well at all so it must be completely sealed. A small leak will ruin all the hay in the exposed area and, with a bit of airflow, can spontaneously combust. More likely, though, is that it just degrades rapidly. Like a lot of things, good planning can keep you fine.
If you’re going to seal it, why not just use mud, clay or whatever ground/dirt instead? Probably won’t need to be as thick to give similar insulation.
Also, what about impact resistance? Can an angry punch break that outer lime layer?
What’s the tallest one of these buildings can get?
Well, because straight earth as in mudbrick (or concrete, normal bricks etc) is not insulation. That’s thermal mass. It stores energy. Insulation (like strawbales) slows heat movement. So you need insulation on the exterior and thermal mass on the interior for a properly thermally regulated building.
At 2 inches thick of limestone, you can sure bust it up with a sledgehammer or similar. A punch won’t do much more than hurt your hand. Still, if you take tools to the majority of homes they break quite fast.
Couldn’t say houw tall they can get but from memory I think I’ve seen 3 stories? Over that you’re talking more full on construction. I’ve seen a 4 story using super bales that was in an commercial carpentry shop
Straw bale houses can be made really well, and are ecologically superior building material. I’ve seen some straw bale houses that are fancy af
Straw bale houses are awesome and have been around for centuries
Structurally timber. Checkmate wolves.
(Yes I know the story.)
