We often receive enquiries across the pond from our US friends although there is quite an established spray foam industry there. One such enquiry was about what one spray foam contractor had done and whether or not ventilation was necessary after the foam had been installed. The answer is not always. We explained and wrote:
Ventilation is typically required to minimise condensation. If the design structure has a proven low propensity to condensation then ventilation is not required. Why vent and lose expensive energy from a building if condensation is not going be a problem?
Ventilation is not required if the spray foam application creates what is known as a ‘warm roof’ or ‘warm deck’ solution since the ‘warm’ to ‘cold’ movement of air is prevented and any moisture in the air is not released as condensation if the installation maintains temperature above the dew point of air. ‘Warm roofs’ in the UK by definition do not require ventilation. Any cold bridging points might be a problem though and still cause condensation unless controlled for.
We are spray foam contractors and the requirement to vent an attic (loft in the UK) space after installing polyurethane foam is not a concern if the job is done properly. We are moving to sealed envelope solutions in the UK for building design (I believe the US is similar on this point) and ventilation is only introduced where the condensation risk cannot be solved by any other method. Condensation needs to be avoided since long term this destroys the fabric of the building, leading potentially to wet and dry rot in timbers, reduces its energy efficiency as wet insulation, particular fibre glass or mineral wool loses all its insulation qualities, and can cause bad air quality which may negatively impact upon the occupants of the building, produce mildew and mould growth etc. Ventilation may help control condensation but only adds to the energy loss of a building which clearly is to be avoided if at all possible.
If you sit in the car without the ventilation open and without allowing fresh air in it is usually not long before the windows mist over which are the coldest surface inside the car. Merely winding a window or two down by a fraction allows sufficient ventilation to avoid this misting or condensation. However, if the windows were coated with polyurethane (not recommended by the way!) then no misting would occur. The air in the car would go stale but ventilation in buildings in areas not used by people (e.g loft spaces) is more about avoiding condensation than promoting fresh air although both are clearly desirable.
The original installer should have the technical specifications of the foam installed which might further answer your question which really is all about the likelihood of condensation occurring in an unvented space (not withstanding the fact that condensation can still occur in vented spaces especially under still air conditions).
From the pictures you have sent, though the installation looks rather ugly by our company standards it should not detract from its fitness for purpose as long as a minimum depth in line with the foam’s specification/performance parameters has been met. That looks to be the case from the pictures. I would not think condensation will be a problem save in very unusual circumstances.
Concerning the cost of installing polyurethane spray foam, polyurethane foam is a high performance product that insulates seals and bonds and requires no ventilation because it creates a warm roof. It is also professionally installed by typically 2 operatives per onsite van. Clearly you cannot get this for the price of an inferior product like mineral wool. The foam specified will be 2 component (polyol and isocyanate) rigid, fast cure foam, British Standard Class 1, fire rated, high density (k value 0.020 W/m2.k) and 95% closed cell affording breathing properties to the timber substrate. This is a high performance product and bears no relation to the cheap canned one component foams either used by our competitors or found in the DIY market. Like all things, you get what you pay for.
The foam will draft proof (air leakage is a major source of energy loss), insulates (reduces transmission of energy by thermal conductivity) and sound proof to a large degree, The depth of foam applied range anywhere from 40 mm nominal to 150 mm nominal and is governed by the U value that is required and the k value (thermal conductivity of the insulation material). Depth of insulation foam is given by factoring the U value required into the k value and normalising for units to get the depth in millimetres. We do this calculation on behalf of the customer and can if required do proof of calculation if these are needed to support a planning application. He have designed the industry’s first U value calculator for composite substrates and will produce a thermal resistance R value as the sum of (R0 + R1 + R2 + … etc) to get the U value needed. From that it is a straightforward to get the depth of foam needed by the foam’s k value - (d = k/U and then normalise for millimetres).
We heat fuse the foam to the substrate at high temperature (120 degrees) and at high pressure (600 psi). We essentially bring a polyurethane factory to the customers door step (a large van with £70,000 of foam making equipment) and make the foam on site. We guarantee the foam for a minimum of 25 years.
Polyurethane foam is the best insulation solution by far and will out perform, products like mineral wool (which always need venting thus creating drafts that suck heat out as mineral wool does not seal) by a factor of 6 to 1 under real world conditions. Laboratory results for calculating U values rely on heat box still air conditions and this gives polyurethane foam a typical performance advantage over mineral or glass wool by a factor of 3 to 1. If you want the best it is has to be a polyurethane foam solution.
IsoSpray now also now supply professional ‘DIY’ of two component foams suitable to be sprayed at ambient temperature. If you are capable of spraying and doing the job yourself then this might help reduce your costs if cost is your primary concern. IsoSpray always guarantee the lowest rates for all products for all work we do.
I often get asked who we think our main competitors are. Well, we only rate 4 other companies in the spray foam industry for competence, technical ability, application skill and having the ability to stick around financially to honour any guarantees. On the latter, must companies don’t last more than a few years without undergoing a metamorphosis and reappearing under a new limited liability company name with risk capital of just £2.00. And we wish some would stop using non rated British Standard Class 1 foams. And we wish they would tell the truth…
But maybe the reader can better appreciate the competition we face with the following spoof enquiry we received.
Dr Nana Bannana
Email: Bannanaskin@hotmail.com
Address: 14 Fruit Village
District: South Glos
City or town: Ding Dong
County: Lalala
Post code: Bs37 89k
Telephone: 01454 678991
Mobile: 07791874555
Comments: u smell like poo
Unfortunately our competitor is a little intellectually challenged as we did an IP trace through one of colleagues in the IT industry and he reported that the IP address was issued by ISP provider serving one of our known competitors (the same IP block has been used before). No, we want name and shame them here because it is quite laughable really. But let us just say this company is based in the North West region of England in a city famed for football. And this is not the first time we have received such rubbish from one of our competitors. We have a file of such enquiries and maybe one day we will publish and name and shame.
I say competitors but really I should not adorn them with even that respect, who would really want to do business with a bunch of school kids masquerading as a spray foam company? To be a valued competitor you would think they would tackle the following: honouring guarantees, do the job right first time, using the right foam, telling the truth to customers, and lastly showing respect to other competitors who do it all so much better.
And who has the time to make spoof enquiries if you are running a successful spray foam company? Our competitors apparently.
Asbestos slates or asbestos tiles are not manufactured anymore for obvious reasons. Health.
But there are literally thousands of homes that have asbestos slates. Asbestos slates were used in abundance in the early part of the 20th century before health concerns were raised using asbestos.
I often get to see an asbestos slate roof and saw another one only yesterday. Most asbestos slate roofs that were installed 70 or more years ago are reaching the end of their useful life. Some asbestos roofs however, typically in more sheltered parts, are still going strong and good for many years to come yet.
Typically what happens is that the asbestos slate will start to become porous though actually not that leaky. The surface of the asbestos starts to rough up and the tips of the asbestos tile start to curl. More often than not the asbestos tile also has an abundance of moss growing on it and has been typically laid in a "diamond" fashion. When the asbestos slate starts to shale (break up in layers) then there is no hope but a new roof. Also, the curling will allow more wind blown rain to blow up into the loft space as at the time these asbestos tiles were laid using a felt protective membrane was a thing of the future to come. The other thing to notice about asbestos tiles is that from inside the loft you will often see water staining like a salt stain on the underside of the tile indicating that water is getting through. Not nice to see water coming into your loft, is it?
Is polyurethane spray foam the answer to a 70 years plus asbestos roof that is showing signs of curling and shaling? No! The reason is simple, polyurethane foam is sprayed from the inside but the major deterioration of the asbestos tile is happening on the outside. Once the asbestos tile starts to rough up and loose its protective surface the tile is on its way out to the tile knacker’s yard in the sky. It becomes porous and will not provide a long term suitable partner to the polyurethane foam.
The job I saw yesterday was a new roof job and not a polyurethane foam job. We as a company also have a professional reproofing team that are kept busy year round doing new roofs. I concluded that this asbestos roof was doomed after just 2 minutes of surveying.
Interestingly, my quote for a new roof was less than one polyurethane foam company had actually quoted to spray in polyurethane foam! As a rule, polyurethane foam installation is less to install by a good third to one half the cost of a relayed roof and has the additional benefits of minimal disruption, excellent insulation and roof bonding. It beggars belief that they should have even quoted for polyurethane foam never mind that they were also trying to charge a King’s ransom for a wrongly specified job! See my previous comments on the going rate price for polyurethane foam!
Commonly known as the big 6 because of the typically 6 inch corrugation, many industrial units built in the last century were clad in asbestos, roofs and walls. These days big sheds tend to be clad in coated steel sheets.
Now a lot of these industrial asbestos roofs are showing signs of age, typically leaking via the bolt holes that were originally sealed by rubber grommets. The rubber perishes, the steel bolt corrodes making it well neigh impossible to replace with new but ideal for leaks to develop. You cure one leak then another appears, a never ending maintenance nightmare. One solution that Isotech have adopted which is very cost effective when compared to the cost of a new roof and the major disruption that would cause a business not to mention the downtime and cost in lost storage and production is to do a "foam and coat" from the exterior. Also, asbestos disposal is a very costly affair these days.
Basically, the exterior of the asbestos roof is cleaned and prepared, then coated with a specially formulated dense foam (you can walk on it without damage) typically to 40 to 50 mm and a final rubberised coating is then sprayed on to protect the foam and provide a strong and waterproof layer. Depending on the quality of coatings and the budget allowed this solution can renovate a leaky old industrial roof and give up to 25 years life before a further coating would be necessary. It also has the additional benefit that the asbestos roof is now also well insulated; 50 mm of foam is typically as effective insulation wise as about 150 to 200 mm of normal mineral wool insulation.
The foam and coat result is a renovated asbestos roof at a fraction of the cost of a re-roof, not to mention the cost of business disruption and asbestos removal, a well insulated thus saving on heating bills and an extended roof life of up to 25 years (depending on quality chosen) before a further top coating will be necessary.
I was called out over the weekend to attend a leaking roof. With all the torrential rain we have had this week I suspect we will be getting quite a few more calls yet. Anyway, this roof visually looked in good order, all tiles were on, none were cracked and all looked correctly positioned. So how could this roof leak?
Well, first thing I noticed was the relatively low pitch of the roof, about 25 degrees. Second thing I noticed was that the tile head cover was only 40 to 50 mm. This is the amount of tile overlap between the rows of tiles. Third thing I noticed from inspecting the roof from inside the loft was the fact that the felt underlay had largely perished and was hanging down in places, clearly passed its sell by date. The felt underlay on shallow pitch roofs and roofs with small tile overlay is pretty much essential.
So how was the roof leaking then? Well, get a bit of wind to blow the rain up through and between the tiles, particularly if the overlay between tiles is only 40 mm, then the rain will clearly enter the loft space if the felt, the barrier of last resort, is in poor condition. Not only that, once water starts to "track" it can continue to run uphill across short distances on relatively shallow pitched roofs without wind assistance. This was what had happened here, a roof that looks apparently watertight actually leaking like a sieve because the water is running up hill due to the tracking.
Try this experiment, hold a tile under a running tap at quite a steep angle and you will notice that the water runs cleanly off and does not run around to the back of the tile but "drips" consistently off from the very end of the tile. Now decrease the angle you hold the tile to the water and low and behold the water runs down the tile but then creeps around under the tile before finally dripping off. This is how water can track uphill and why felt underlay is essential on very shallow pitched roofs and this becomes the waterproof layer, not the tile.
The solution? Well, I have to admit that spraying with polyurethane foam might appear to be an answer but this would not be a good solution. To enable the roof timbers to breath, the polyurethane sprayed has to be semi permeable type and the type used is typically 95% closed cell, loosely meaning that it is 95% waterproof. So, in a continuous and sustained soaking of the polyurethane it will gradually absorb water and with a shallow pitched roof of say 25 degrees or less and with less than say 100 mm tile head overlap this is more than likely, absorption to the point it leaks again. One solution would be to strip and re-felt the roof and then relay the tiles. A better solution would be to retile with greater head overlap and an even better solution would be to redo the roof timber carcass and increase the pitch to 30 degrees or more - more is better.
I was asked to look at an old Cotswold stone barn roof this week.
It was built originally around 1860 (the owner believed) and was in need of some TLC, quite a lot actually. Now back then these roofs were constructed by laying stone tiles on mortar beds across supporting laths, a bit like laying bricks since the stones clearly did not have nips to grip laths. Then they would finish off the inside by pointing between the laths with a mixture of horse hair and plaster mortar, the horse hair helping to secure and strengthen the bonding. I suppose in its day not a bad solution and probably looked quite neat by the time a skilled tradesman had finished, clearly not a job for a novice.
The condition I saw it in, however, was far from neat. Most of the pointing was perished, stone tiles had slipped or were missing, water had clearly been penetrating the roof for quite some time and internal pointing between laths was mostly hanging off. A mess really.
Now the reason I was there was to assess if this roof could be rescued using polyurethane foam. Sadly the answer was no. The foam to act as a bonding agent to prevent tile slippage most clearly be attached to the underside of the tile, in this case this would have been well neigh impossible because of the decayed pointing and mortar beds being in the way and there being no way this could be effectively removed without moving the tiles from the roof. Also, the fact that the roof needed major stone replacements, a lot were cracked or missing completely, meant we had a very leaky roof unsuitable for foam application without a lot of remedial work, a very lot! My view was that the roof had been left too long in a bad state of repair and had decayed to the point were only a re-roof would do justice to the job. Now, the customer was reluctant to do a re-roof since he had worked out that he would need the best part of 20 tons of stone tiles at £2000 per ton! And the fact that he has estimated that he would recover no more than 2 tons from the existing roof due to the overall bad condition. He was also in a conservation area which meant that he did not have an option about the roofing material; it had to be Cotswold stone period.
I left giving a price estimate but I think the job is down to affordability, it clearly is going to be an expensive re-roof due to the materials and not one that can be solved using polyurethane spray foam.
I am sure that when customers start to think about having polyurethane spray foam that they naturally want to get a going rate price so that they don’t end up being ripped off. They typically try to achieve this by inviting several companies to quote. What they normally get is those companies that catch their eye to begin with and a company that has a salesforce to feed with high sales commission rates. What I do find interesting is that Isotech, being considerably cheaper, is not even close to the alleged going rates that some companies would have you believe. Ignorance of prices lead some householders to being well and truly ripped off.
I was in Devon earlier this week, always a nice part of the world to travel around. I met a customer who had had a quote from another company that was over 1/3 higher than IsoSpray’s quote. And this higher quote was for less work too! I was stunned when he told me the rival quote after I had quoted.
Now, we are in business to make a profit too but not at rip off prices. Needless to say, we won the contract. Customer happy, we are happy, rival company not happy: You are destroying the profit margins I think they said. No, we are putting an end to greedy company owners and putting sanity back into the market and establishing a true going rate for installed polyurethane spray foam.
One thing I hate his deceit and lies. Why do some salesmen then, in an attempt to close the sale, come out with the line: I can knock pounds off to night if you sign up now as we have another job around the corner that by twinning with job with help my company save pounds. I raise it because we gained a new customer yesterday who precisely refused to fall for this line. Not only is it unprofessional but 9 times out of 10 the job around the corner is a lie. Apparently up until the salesman concerned came up with that line he was going to get the order! Thankfully, we don’t employ salesmen so we can’t lose customers on false sales lines.
A question a customer asked was: How hot is the polyurethane foam when it is sprayed? Well, the answer is that it varies between about 100 C to 130 C depending on ambient temperature.
The polyurethane foam is sprayed on at this temperature because it sprays well at a high temperature (when it is cold it is very sluggish) and gives a good spray. It also ensures very good bonding to the substrate, typically a slate or tile. Also, the typical pressure for the spray foam is 60 pounds per square inch. In effect, at 120 C and 60 psi the foam welds to the substrate and ensures excellent bonding. To ensure that the foam reaches (via the flexible delivery pipes) the spray gun at a high temperature it is firstly warmed up by a heating block. Additionally the foam delivery pipes to the spray gun have electrical heating elements along the length that can be regulated to maintain the temperature of the foam from its journey from heating block to the spray gun. This is particularly important in winter months when the pipe run would cause the foam to cool down too much before delivery to the spray gun. On very cold days it is also necessary to heat the twin chemical drums to get sufficient low vicosity to enable the pumping process to start.
Now, all this specialist spray foam gear is quite expensive and also very high maintenance but essential if a professional job is to be done.
The Mad Surveyor 
