Best construction method to avoid mould growth

[goatcarrot]

I’m extremely hypersensitive to mould spores having spent my life living in damp old buildings.

 

I have the opportunity to build a near PH house and I want to do as much of the labour as poss (I’m a spark, pv installer, I can plumb, do joinery, plastering and general building) to keep costs down.

 

I’m considering timber frame sips constructed on site as crane access is difficult. can get a builders merchant wagon or concrete truck in though. 
 

I do have concerns about injected cellulose and the worry that if any moisture breaches the panel I could have unseen mould growth which might somehow be picked up by the MVHR. 
 

I’m also trying to avoid potentially toxic building products as I’m more sensitive to my environment than most people but realise that I need a balance between synthetic and natural to find the right performance.

 

what other construction methods would suit me? 
 

planners might insist on local stone facade to fit in so traditional cavity wall could work but I’ve never laid block so would have to employ someone. 

Am I worrying too much? I know the PH airtight layer and MVHR mean moisture in the living space is controlled but what about moisture from the outside? We are up north near the lakes so it can get pretty wet and the location is semi exposed. 
 

any views welcomed. 

 

[Big Jimbo]

Good luck. Are you thinking of making your own sips panels ?

[goatcarrot]

31 minutes ago, Big Jimbo said:

Good luck. Are you thinking of making your own sips panels ?

Yes from a kit

Edited January 29, 2021 by goatcarrot

[Big Jimbo]

Sorry, are you intending to buy pre made sips panels, or make your own ?

[joe90]

Welcome, I thinK MVHR is a must for you with your condition,  blown cellulose is a pretty non toxic material (AFAIK). And “plastic” insulation is a petrochemical product. I built in brick and block with rockwall batts as insulation (200mm) . Good on you fir doing what you can but you might find it is worth paying a block layer as they will be faster and more accurate (sorry) than you, you will be busy enough being his labourer. I paid a main contractor for all concrete, brick, block, plastering, roof stuff but was busy full time along side them doing everything else.

[goatcarrot]

15 minutes ago, Big Jimbo said:

Sorry, are you intending to buy pre made sips panels, or make your own ?

I think I’ll have to make my own as access to the site would be tough for a big crane. Telehandler would get in though. 
 

also open to other methods of construction (ICF?) 

[goatcarrot]

I’m just trying to find the right method considering all the constraints 

 

no mould growth anywhere

doing as much as I can myself

budget

non toxic materials 

[Big Jimbo]

I would be concerned that you would not be able to get your own sips panels certified.

[goatcarrot]

2 minutes ago, Big Jimbo said:

I would be concerned that you would not be able to get your own sips panels certified.

I’m not fussed about PH certification, just the performance. Obviously resale value is a consideration though

[Big Jimbo]

I'm talking about having your sips panels signed off. Building control, or an engineer. I doubt you will get either to do it. Sips panels are made in a factory under high pressure. If you decide to either stick build or timber frame, you will still have to find somebody to sign it off.

[jamieled]

I'm not sure if you can build SIPS panels using blown cellulose as the insulation. Wouldn't you need rigid insulation for SIPS?

How about either stick building a timber frame on site with a breathable wall buildup or the same using small panels?

[goatcarrot]

6 minutes ago, Big Jimbo said:

I'm talking about having your sips panels signed off. Building control, or an engineer. I doubt you will get either to do it. Sips panels are made in a factory under high pressure. If you decide to either stick build or timber frame, you will still have to find somebody to sign it off.

I’ve been speaking to a well known firm and they supply kits to be built on site using this method with cellulose blown in after construction, maybe I’ve got the terminology wrong and it isn’t called sips

[SimonD]

32 minutes ago, goatcarrot said:

I’ve been speaking to a well known firm and they supply kits to be built on site using this method with cellulose blown in after construction, maybe I’ve got the terminology wrong and it isn’t called sips

 

I think you may be referring to timber frame panel systems rather than sips. These panel systems can be open or closed, filled with different types of insulation, including pumped cellulose or woodfibre, sometimes done in the factory, sometimes completed onsite. With your allergies and sensitivity to mould, thus wanting to avoid excess moisture, I'd recommend you have a look at woodfibre breathable systems as the fabric of the building due to its moisture buffering capabilities.

 

However, seeing your original post and that you have difficult access, stick frame may be the option, unless you can fit something like a spider crane in there?

Edited January 29, 2021 by SimonD

[goatcarrot]

@SimonD  thanks I’ll have a look at woodfibre open systems. Spider crane could be an option to lift the ridge beam in. 

[ToughButterCup]

1 hour ago, goatcarrot said:

...

Am I worrying too much?

...

 

No, as long as you are sleeping OK. If the issue gets in the way of sleep, yes, you are.

You might think that you are over-thinking: everyone does it. Yes even His Holiness @Russell griffiths . A while ago I got a bit p1$$ed off about how much I worried - I'm not a (so-called) Girl's Blouse either. So I wrote (2016)  about it in my blog - (I used to train serving teachers and undergraduates)

 

Quote

I'm sometimes accused of overthinking stuff. And I'm a little weary of it. Here's why.

Expert status in many areas is thought to develop after about 50,000 hours of practice. And one of the common characteristics of expert status is the reduced need to think about the hard-learned craft or subject. It (irrespective of subject matter) becomes hard wired. 

 

Take my digger. Just bought it a few weeks ago and while using it in the first couple of hours I was like a cat on a hot tin roof. My shoulders ached, my jaw was locked, my concentration fierce.

And then I remembered my flying lessons. 'Think it, and it'll happen, lad ' growled the instructor. And when the fear had dropped a bit, I allowed myself to relax and reduce the control inputs. Suddenly I wasn't dancing all over the sky like the proverbial in a pot. On the digger, I reduced the control input and slowly the swing was not so large, not so jerky. Then Ed (Construction Channel) said it would take about 4 hours to get a basic understanding. He was right.

 

That was a fortnight or so ago. Now, I couldn't tell you what I do to hook a self-hitch bucket, Now I get annoyed at myself for 'clangy' bucket movements.

Slowly I have stopped thinking about it. I just feel it. The next step is over-confidence (pilots call it the Death Zone -about 200 hours into their training). Now, I don't think I'm going to die while using a digger, but I'm going to be extra vigilant in a month or two.

 

After many hours of practice, experts (it's a well-documented phenomenon) simply don't remember that they had to learn stuff. And sometimes are just a little puzzled by someone who asks apparently naive questions. And then -with kindness and reassurance at the root of their response- reply that the questioner is over-thinking it.

 

No, all the questioner is doing is sharing their worry, their lack of expertise, their lack of practice. 

 

Of course you aren't experienced in PH building processes - yet. So you will think about it - share your worry, and we'll help.

Ian

[ProDave]

Mould growth is a result of cold walls (poor insulation) and condensation forming. Not helped by poor ventilation leaving moist stale are lingering.

 

I don't expect you have this problem with ANY modern method of building with a decent level of insulation and importantly with everything well detailed.

 

Then add mvhr to ensure fresh eficcient clean dry air and the chance of mould is nil,.

 

[goatcarrot]

Thanks for the replies and readiness to share experiences. It’s just a bit daunting knowing I’ve got a good chance to reverse the habit of a lifetime and provide healthy housing for me and my family. 
 

my main worry was the possibility of mould forming in the fabric/cavity but I’m glad to hear that’s considered unlikely/impossible if done right. 

[ToughButterCup]

Dim bits of my memory tell me I have some research data on PH and mold. If I bump into it, I'll post it.

[goatcarrot]

1 minute ago, ToughButterCup said:

Dim bits of my memory tell me I have some research data on PH and mold. If I bump into it, I'll post it.

Awesome thanks

[Temp]

+1 To MVHR. Best thing we included in our house.  I'm convinced good ventilation is key to keeping humidity and mould down. Avoid any alcoves or recesses where air cant circulate.

 

I would also consider UFH and a combination of engineered wood and stone flooring instead of carpet. 

 

 

[ToughButterCup]

Here you are: it's a doctoral thesis I bumped into at work........ here's the abstract 

 

Quote

Policies related to the reduction of both carbon dioxide emissions and energy consumption within  the residential sector have contributed towards a growing number of passive houses and other
highly energy-efficient dwellings being built in many countries. Since these dwellings are very well  insulated and airtight, concerns have been raised over the quality of the indoor air and, consequently, the possible health effects for their occupants. Additionally, following well established evidence from the residential energy consumption literature, it has been considered vital to explore occupants’ practices when trying to understand possible contributions to the quality of the indoor  environment in passive houses, and thus any potential effects to the health of occupants.
Nevertheless, very little research has explored this issue.

 

This longitudinal, mixed methods, interdisciplinary study has collected and analysed qualitative data (from house occupants’ interviews and diary) and quantitative data (from the monitoring of the indoor climate and indoor air quality) over three different seasons (winter, spring and summer) from different rooms in five passive houses and in four conventional (control) houses in the UK.

 

Additionally, data has been compared with reviews of epidemiological, toxicological and other health related published studies to reveal the following:

• Passive houses can provide either a potentially healthy or unhealthy environment for their occupants, depending on the hazard being analysed. For instance, when analysing indoor temperatures, passive houses were found to be potentially healthy during cold months but potentially unhealthy during the summer.
• On the other hand, the analysis of relative humidity levels suggest that passive houses are potentially heathy during the summer and potentially unhealthy during the winter.
• Potential health risks in passive houses were caused by one or a combination of variables, including passive house design and construction and occupants’ practices. 

(my emphasis and re-formatting for legibility) downloaded 29/01/2021

 

Here's the whole study from sciencedirect.com  https://www.sciencedirect.com/science/article/pii/S1876610215023413

[goatcarrot]

@Temp yes no doubt here either as long as filters are up to the job and changed regularly. 
 

+1 for no carpet. Soft thick rugs on engineered wood works for me

[goatcarrot]

@ToughButterCup

 

thank you, I’ll have a delve. 
 

Yes, creating a sealed box that relies on mechanics and technology to keep air fresh and humidity low is all very well unless something goes wrong in which case you could be pumping bad air around.
 

I’m sure this is still unlikely but it’s intriguing that there’s not much real world data. 

[goatcarrot]

@ToughButterCup

 

Interpreting scientific papers ain’t my strong suit but the report appears to confirm that the risk is small however, still a risk. 
 

I wonder how this compares to a block and insulated cavity type build or ICF. 
 

the nourishment that mould needs is dead organic matter so wood/cellulose is the perfect food, perhaps concrete/stone/block/foam it is even less likely. 
 

comments welcomed/appreciated 

[goatcarrot]

I suppose the question is, if some mould is unavoidable in the fabric/cavity, no matter the construction, will MVHR filters prevent any spores entering the living space?