[Peter Dow (OP)]

You can buy spray foam for use as a fire-stop, but I wasn't impressed that it seems to burn quite readily.

Your normal fiberglass as used in roofing, or bathtubs will also burn, releasing a nasty black smoke...  don't ask how I know!  The resin burns out, leaving the glass fibers behind.

But how easily is GRP to get burning and would it keep burning without another heat source? How does that compare to how easily normal expanded polystyrene burns?

GRP burn test - A guy puts a blowtorch on a disc he says of GRP and it holds up pretty well. San Juan Fiberglass pools burn test (YouTube)

Well that example is maybe not normal GRP, possibly he is using a resin that is more fire-resistant or maybe he has a high percentage of fiberglass to resin which protects the resin underneath?

EP burn test - Burning Polystyrene (YouTube)

I don't think I'd be too keen on a "floating house" in most flood prone areas.

Well it sure beats a submerged house.

It would need a lot of excess buoyancy to hold up the appliances and etc, and not flood the floor.  Like building a house boat on land.

Many floods like tsunamis, and some river associated floods have a strong current associated with them, so a floating house would tend to float away, or if tethered, it would be subjected to extreme stress.

There may be some places, such as in the Amazon where it floods annually, and one might choose to build a type of house designed like a houseboat that could raise and lower with the water level.

Now, I'm not saying that there would not be some need for temporary shelter.

I was thinking more in terms of a temporary raft shelter for people and their most valuable possessions to ride the flood out. Also people don't usually get flooded out by a tsunami or a dam bursting. Yes that would be extreme stress and sweep away most things but normal flooding you can anchor things that float and there's no extreme stress, unless you forget to tie it up, it floats away when you were not looking, you lose it, and that might "stress" you and make you cry maybe.

Foam blocks might be unwieldy to ship.

Why? They can be transported in nets bundling them together in numbers and a weight to best suit the transportation and cargo-handling equipment in use.

However, I could imagine a house in a 50 gallon drum (or two).
One drum might contain a double walled tent.  The second drum might contain a spray foam.

Unpack and inflate your tent.  Then, spray in the foam.  Let it dry overnight, and you would have a good "temporary" structure the next day.  Add a durable outer layer (metal sheeting, or concrete/stucco), and it might actually last fairly well.  Could you reinforce it with fiberglass?

You seem to be envisaging manufacture and assembly at the same point and time. That's too slow and ordinary people, especially suffering a flood disaster. don't have the time and the expertise to manufacture anything complicated, but maybe they can assemble and it is better if the assembly is quick and easy, as would it would be with an I / H brick & dowel structure, with the bricks and dowels manufactured in factories by mass-production techniques and later assembled on site.

There are also a number of manufactures of foam concrete forms (or insulated concrete forms) which can provide the insulation properties of foam, and mass and durability of concrete and rebar.

I presume those assemble with mortar? The advantage of the I / H brick & dowels would be that the pieces simply slot together.

[David Cooper]

If a hole is punched in the outer covering and fire gets in through it, the gas inside the polystyrene could make a substantial difference to the rate of spread of the fire within the wall. If it burns more slowly due to a lack of oxygen other than the little that can get in through the hole, that will give people more time to take action, though it could also go unnoticed for a long time and release lots of carbon monoxide.

For floods, if you live in a hut and occasionally have to take to the roof when it floods and hope that the water won't go higher than that, a lightweight top floor which can detatch and float on a tether would be useful - there aren't always strong currents. There may be other issues with strong winds though.

I see the main benefit as being with emergency housing in earthquake zones, though they'd need to be kept small enough that it's easy to clear snow off the roof as it may not be able to support more than a few inches of the stuff. Tents are freezing, but these could be kept warm much more easily and could be lived in relatively comfortably for long enough to span the gap while proper houses are rebuilt.

[Peter Dow (OP)]

If a hole is punched in the outer covering and fire gets in through it, the gas inside the polystyrene could make a substantial difference to the rate of spread of the fire within the wall. If it burns more slowly due to a lack of oxygen other than the little that can get in through the hole, that will give people more time to take action, though it could also go unnoticed for a long time and release lots of carbon monoxide.

Like I said, the gas is not air, it is a gas picked for the job of blowing bubbles and they don't pick oxygen and they don't and won't pick the gas you recommend. Sorry David but no-one is listening as far as my-favourite-gas-in-polystyrene-bubbles-wish-list is concerned. It's like the early Ford cars - you can have any colour so long as it is black. Well different manufacturers might use different gases as blowing agents, I don't know, but in truth it's academic because it is not going to make any difference to how the E.P. burns.

For floods, if you live in a hut and occasionally have to take to the roof when it floods and hope that the water won't go higher than that, a lightweight top floor which can detatch and float on a tether would be useful - there aren't always strong currents. There may be other issues with strong winds though.

Well you can tie it down to resist winds too. Whatever we suggest people would store them their own way.

I see the main benefit as being with emergency housing in earthquake zones, though they'd need to be kept small enough that it's easy to clear snow off the roof as it may not be able to support more than a few inches of the stuff.

Oh well with angled bricks it ought to be possible to build sloping roofs that the snow slides off.

Tents are freezing, but these could be kept warm much more easily and could be lived in relatively comfortably for long enough to span the gap while proper houses are rebuilt.

What I worry about more is if the aid agencies give these bricks out for free to people in a disaster zone to make rafts or shelters out of then after the present flood has drained away or rebuilding begins after an earthquake then the people may well misuse the bricks they were given, burn them for fuel or whatever in a short-sighted way that destroys the bricks and is neglectful of the fact that they'd need them for the next disaster. If you give people stuff for free they don't tend to value it as much as if they have to pay for them even if it is only a token amount, less than the production cost, something they or their government can afford but enough so that the people value the bricks and don't waste them after all the trouble we went to designing, building and distributing them.

[CliffordK]

Sorry, I didn't make a comparison of different spray foams.  But, I didn't find the firestop very fireproof.  This was a burn test I did a couple of years ago.  It was easy to light.

 [ Invalid Attachment ]

I think the idea is that if you fill a crack, it will slow down the progression of flames and smoke through the crack, but it will certainly burn quite nicely.

[CliffordK]

There are many different types of floods.

In the Northwest USA, the floods are characterized by fast moving water, capable of ripping houses from their foundations, and certainly not safe to casually walk in.  The 1964 Rogue River flood had a depth of about 10x the normal river depth, 68 feet at Agness, 50 feet above flood stage, or about 4x what is considered flood stage, and flows exceeding 100x the summer flow rates.  And, no dam failures.

Mississippi River floods may be slower moving. 

Although, there still may be periods of rapid inundation as dikes fail, followed by slow moving water once a basin fills up.

I presume that during flood periods, most people simply move away from the water.  I'm surprised of the number of people walking around in the  Bangladesh flood above.  The problems with shelter comes as people return to their homes.

A simple concrete structure may be able to withstand the flooding, although one of the issues noted in New Orleans was that mold became a significant issue, and much of the insides of the houses needed to be gutted and rebuilt, or even the whole houses torn down after the flood.

It may be more intense building, but some houses may be built on stilts, or in rural areas, perhaps building a small hill for the homesite which then remains as a small island.

For slow moving flood prone areas, It would be easy enough to build a house with wood, or hollow skids underneath it, and chained down to prevent it from floating away.  Of course, being careful of boyancy/weight of construction materials.  For a high flow area, a floating house may still sustain significant damage.

[Peter Dow (OP)]

Sorry, I didn't make a comparison of different spray foams.  But, I didn't find the firestop very fireproof.  This was a burn test I did a couple of years ago.  It was easy to light.

 [ Invalid Attachment ]

I think the idea is that if you fill a crack, it will slow down the progression of flames and smoke through the crack, but it will certainly burn quite nicely.

Burns "nicely" so long as no-one is breathing in the fumes.

Wikipedia: Polyurethane - Health and Safety
Polyurethane polymer is a combustible solid and can be ignited if exposed to an open flame. Decomposition from fire can produce mainly carbon monoxide, and trace nitrogen oxides and hydrogen cyanide. Firefighters should wear self-contained breathing apparatus in enclosed areas.

Yet that is supposed to stop a fire spreading?

Out of interest, did you just spray it and light it immediately or leave it for a time to set, if so for how long?

I ask because I read a website that said their product is supposed to set over time by reacting with moisture in the air. Possibly when it comes straight out of the can it is a lot more flammable than it is after setting?

Not that I am recommending this product. I am with you if you are questioning its utility.

[Peter Dow (OP)]

There are many different types of floods.

In the Northwest USA, the floods are characterized by fast moving water, capable of ripping houses from their foundations, and certainly not safe to casually walk in.  The 1964 Rogue River flood had a depth of about 10x the normal river depth, 68 feet at Agness, 50 feet above flood stage, or about 4x what is considered flood stage, and flows exceeding 100x the summer flow rates.  And, no dam failures.

Mississippi River floods may be slower moving. 

Although, there still may be periods of rapid inundation as dikes fail, followed by slow moving water once a basin fills up.

I presume that during flood periods, most people simply move away from the water.  I'm surprised of the number of people walking around in the  Bangladesh flood above.

Well I am no expert on Bangladesh but I can read that the floods there can inundate 50% or more of the land area and so maybe 30 million homes are flooded and people may be 50 miles or more from any dry land and my guess is that their local and national authority emergency relief services can't cope and so people are left to fend for themselves at least until the news photographers turn up, hopefully soon followed by the international aid agencies.

The problems with shelter comes as people return to their homes.

A simple concrete structure may be able to withstand the flooding, although one of the issues noted in New Orleans was that mold became a significant issue, and much of the insides of the houses needed to be gutted and rebuilt, or even the whole houses torn down after the flood.

It may be more intense building, but some houses may be built on stilts, or in rural areas, perhaps building a small hill for the homesite which then remains as a small island.

For slow moving flood prone areas, It would be easy enough to build a house with wood, or hollow skids underneath it, and chained down to prevent it from floating away.  Of course, being careful of boyancy/weight of construction materials.  For a high flow area, a floating house may still sustain significant damage.

Well not all houses can survive a collision with what the flood brings to its door, or its roof.


A ship was washed onto a building when the city of Otsuchi, Iwate Prefecture, was hit by the tsunami.

For this kind of strength I don't think expanded polystyrene can help us. I / H bricks made of reinforced concrete could do that boat-on-the-roof job though.

[Peter Dow (OP)]

HI-BRICKS & DOWELS demonstration video by Peter Dow (YouTube)

Transcript of the video



Hi everybody and welcome to my "H" / "I" Bricks or HI-BRICKS & DOWELS demonstration video.

This is Peter Dow from Aberdeen, Scotland.

There are two components to a HI-BRICKS & DOWELS construction -

• the BRICKS, which you can either describe as "H"-shaped or "I"-shaped, depending on which way you turn them around
• and the DOWELS

The shape of the "H" or "I" bricks is designed so that they fit together to form a layer or a wall of bricks and importantly, the bricks, just by their very shape, immobilise each other from moving, in one dimension only.

Let's have a look at that.

Let's consider this green brick here as the fixed point.

We can see that it immobilises its neighbouring bricks in one dimension. They can't move with respect to the green brick in this dimension. So that's locked. Even though there is no bricks here or here, the very shape stops it moving in that dimension.

Now the shape doesn't stop the bricks moving with respect to each other in that direction, or in that direction but they are fixed in that one dimension.



Now if we want to make a rigid structure of bricks in all three dimensions but without using mortar or glue so that we can assemble and disassemble the structure whenever we like, what we need next are the DOWELS.

As you can see, the "I" or "H" bricks have shafts running through the corners so that you can run a dowel through the corners - two shafts, four holes per "I" or "H" brick.

And when you assemble the bricks you can slide the dowel in ... and this forms a structure which is rigid in all three dimensions, which is what we need to form structures.