No more Tin on Roof for me??

[ebee]

I have tin galv and alu clad hive roofs. In the strong sun the steel roofs feel hot but the alu ones are cool. Why is that? Is it something about reflective qualities?

 

[Karol]

Insulation beneath the roof will solve that.

Hmmm! I would remain to be convinced. IMHO it would probably make things worse. Now, ventilation on the other hand, might do the trick.

 

[Karol]

I have tin galv and alu clad hive roofs. In the strong sun the steel roofs feel hot but the alu ones are cool. Why is that? Is it something about reflective qualities?

Mainly reflective qualities but also thermal conductivity and thermal inertia (mass).

 

[Into the lions den]

Rubber is notorious for absorbing and retaining heat especially if it is matt and black. It might be worth trying a single roof at least during one hot summer to ensure the bees don't cook out.

Black asphalt roofing felt (think stuff) is another relativey traditional covering for wooden roof making. Will be very bit as absorbent as this rubber material. About 75% of our Smith roofs were felt covered.

Where this rubber material will have an advantage over felt will be in durability. Felt could last a lifetime if handled the right way, but if there was any ice on the roof and the rock/brick on top was frozen down you could tear the felt removing it. It was also susceptible at the edges to hive strapping. To get this issue in proportion, we probably damaged one of two a year that way out of hundreds.

Key will be prices. Currently costs about 2.25 to cover a roof, and if this product costs more it will only have a very limited market, mainly to those who like to be different.

 

[Cazza]

My first thought is, "only a 10 year guarantee?" Some of mine are at least 30 years old and still going strong.
Cazza

 

[Russel]

Black asphalt roofing felt (think stuff) is another relativey traditional covering for wooden roof making. Will be very bit as absorbent as this rubber material. About 75% of our Smith roofs were felt covered.

Where this rubber material will have an advantage over felt will be in durability. Felt could last a lifetime if handled the right way, but if there was any ice on the roof and the rock/brick on top was frozen down you could tear the felt removing it. It was also susceptible at the edges to hive strapping. To get this issue in proportion, we probably damaged one of two a year that way out of hundreds.

Key will be prices. Currently costs about 2.25 to cover a roof, and if this product costs more it will only have a very limited market, mainly to those who like to be different.

It's about £7 sq m depending on quantity, if we're talking about EPDM which as been around a while now. firestone-epdm-durable-membrane-standard-grade-1-14mm

Russ

 

[user 6228]

Hmmm! I would remain to be convinced. IMHO it would probably make things worse. Now, ventilation on the other hand, might do the trick.

BJ is correct on this one... insulation adds resistance to heat flow in both directions. 100C on the other side of 50mm kingspan can be hardly felt by the naked hand (less than 150mW into your palm or 6W for the whole roof). The bees wont cook out from their own heat because bees natural behaviour can cope with much higher all year round insulation levels than beeks have ever provided. Bees can commonly utilise 200mm of oak insulation for the sides and 5000mm of oak on the roof.

 

[Karol]

Black asphalt roofing felt (think stuff) is another relativey traditional covering for wooden roof making. Will be very bit as absorbent as this rubber material. About 75% of our Smith roofs were felt covered.

Where this rubber material will have an advantage over felt will be in durability. Felt could last a lifetime if handled the right way, but if there was any ice on the roof and the rock/brick on top was frozen down you could tear the felt removing it. It was also susceptible at the edges to hive strapping. To get this issue in proportion, we probably damaged one of two a year that way out of hundreds.

Key will be prices. Currently costs about 2.25 to cover a roof, and if this product costs more it will only have a very limited market, mainly to those who like to be different.

OK, it's not something that I'm going to labour over but felt and rubber behave very differently and most top coat felts have a green mineral finish to reflect heat.

What wasn't clear from the OP was the construction, i.e. whether it's a thin layer of rubber mounted onto a wooden board (viz traditional felt construction) or a 'solid' rubber construction. Again there would be a difference in performance.

So long as the point has been raised for consideration then the job's done. No point in un-necessarily over stressing bees during very hot weather.

 

[Karol]

BJ is correct on this one... insulation adds resistance to heat flow in both directions. 100C on the other side of 50mm kingspan can be hardly felt by the naked hand (less than 150mW into your palm or 6W for the whole roof). The bees wont cook out from their own heat because bees natural behaviour can cope with much higher all year round insulation levels than beeks have ever provided. Bees can commonly utilise 200mm of oak insulation for the sides and 5000mm of oak on the roof.

Agreed it does insulate in both directions but that assumes that there is a temperature gradient which assumes heat is being dissipated and that's down to ventilation. Adding a 'heat' sink to the top of the hive just needs a little thought.

As for your analogy to oak then that belies the fact that trees cool themselves down through evaporative processes and draw tonnes of gallons of water through themselves to do so, so actually, the environment inside an oak is actually pretty well climate controlled and not insulated per se.

 

[Jimmy]

Are we talking about rubbeco? See their vans round here.

 

[mbc]

As for your analogy to oak then that belies the fact that trees cool themselves down through evaporative processes and draw tonnes of gallons of water through themselves to do so, so actually, the environment inside an oak is actually pretty well climate controlled and not insulated per se.

Indeed.
We think of a colony of bees as a superorganism, whereas an oak tree is a whole climate controlled ecosystem which might encompass a bee colony or two as well as a whole host of other creatures and organisms.

 

[user 6228]

Agreed it does insulate in both directions but that assumes that there is a temperature gradient which assumes heat is being dissipated and that's down to ventilation. Adding a 'heat' sink to the top of the hive just needs a little thought.

As for your analogy to oak then that belies the fact that trees cool themselves down through evaporative processes and draw tonnes of gallons of water through themselves to do so, so actually, the environment inside an oak is actually pretty well climate controlled and not insulated per se.

Your reply could be misleading to others . So for their sake I will clarify

Assume bees like 34C so +100C is the same temp differential as -66C.
the heat flow is still only 6W.

As regards "heatsink".. If the surface area has not been increased, or the emissitity or refectivity been not been signifcantly adversely changed, the description "heat sink" does not fit unless you are attaching extra passive or active air moving features.(didnt notice that being mentioned)

Further A tight fitting cleanish aluminum roof reduces heat loss and heat gain rather than increase it
However The emissivity and reflectivity of the rubber is probably no different to tar paper.
Thus the rubber roof with insulation underneath is within the range of conditions that bees are subject to

Tree nests.

The bulk cooling is at the leave stomata where the water evaporates thats 10m+ of oak away so is irrelavent.

The water flow is through the vascular cambium which is in the outmost layers and this flow stops in winter.

This part of the tree is relatively uninsulated and the water flow can be regarded as being at ambient temperature by the time it gets to 5m (typical bee nest height) and is therefore insignificant.

The bulk insulating the bees is secondary xylem which has water content but no water flow.

 

[Into the lions den]

OK, it's not something that I'm going to labour over but felt and rubber behave very differently and most top coat felts have a green mineral finish to reflect heat.

The stuff we use is black, with some sand on it. Not green at all, but I know the stuff you mean, and it would be too exensive.


Its main advantage? Nothing to do with heat as to be honest we see little difference so regard the heat debate as a sideshow. It means hives stacked on top of eachother for transport do not slide about. Much easier to secure the load when you do not have slippy interfaces in the stack.

Whats on all our new roofs for the wooden hives? Metal. 8 quid a roof delivered for E. Europe, fully assembled with metal on. Price influences choice lol.

 

[theeggman]

We've been using offcuts of butyl pond liner on small chicken shed roofs for years.
In fact we roofed a new summerhouse with EPDM 2 years ago as standard felt won't stay on in our windy site.
The 'rubber' is very flexible for going around corners etc. and stays in place with either short clout nails or staples. You can also get a 2" wide black double sided mastic tape to join it or 'glue' the edges to the sub-strate.

Tim

 

[CleanShirt]

I've just built my 1st hive (a copy of a layens hive i bought), i've fitted it with a tin roof, but i'm concerned about the amount of heat it will generate in summer. (i live in southern spain, where the summers are scorching)......I've just had an idea, i could fit a piece of rubber car mat over lid, or will this insulate the hive more making it hotter inside?

 

[peteinwilts]

does anyone use wood sealer, something like yacht paint?

 

[itma]

... i've fitted it with a tin roof, but i'm concerned about the amount of heat it will generate in summer. (i live in southern spain, where the summers are scorching)...

I think a layer of insulation board under the roof would be a better idea.
DerekM would doubtless suggest making the roof out of insulation board!
No knowledge of Spanish brands but if you Google for Xtratherm, Recticel, Celotex and Kingspan you should find something useful.
Skinned with thick aluminium foil on both sides, with 5 cm (or more!) thickness of very fine-grained polyurethane foam in between - that's what you should be looking for.

 

[CleanShirt]

Hi, i should of been more specific. the lid is made from 20mm thick marine ply, with a tin cover. but thanks for the info, 5mm insulation will be just the ticket.

 

[user 6228]

Hi, i should of been more specific. the lid is made from 20mm thick marine ply, with a tin cover. but thanks for the info, 5mm insulation will be just the ticket.

it think itma meant 50mm not 5mm. 25mm of poly foam is definitely the minimum IMHO.

 

[itma]

it think itma meant 50mm not 5mm. 25mm of poly foam is definitely the minimum IMHO.

Yes, 5cm not 5mm was indeed what I suggested.
Regardless of the ply thickness.

It is not expensive, even buying small size sheets (which are convenient to transport but give bigger cutting losses) -- for example at Wickes http://www.wickes.co.uk/celotex-cav..._ggl_0006635&gclid=CMjsut672bUCFfLLtAoduzUAqQ