Battens over pebbledash?

[Kmurphy]

One of my garage walls is pebbledashed - I assume it was an external wall way back when.

Would be great if occasionally with a heater and dehumidifier I could dry clothes there.

I was thinking I would use basic battens and an eco foil, with board over the top. Anyway. To batten the pebble dashed wall, do I have to chip off some of the dash? Is there anyway to get a sensible flat wall?

I can build a drywall with an air gap, but seems OTT for target use

 

[blup]

Broadfix do different thicknesses of plastic shims including U shims, which combined, if necessary, with some localised chipping on the pebble dash should give you a flat surface

 

[robinbanks]

Would be great if occasionally with a heater and dehumidifier I could dry clothes there

You can buy those things all in one box, and they dry clothes regardless of the kind of wall covering they're placed next to

Tongue in cheek tumble dryer recommendations aside, just screw the battens over the top of the dash. On average they will be straight and true enough to plasterboard over with no special treatment. You'll need to insulate the place for a heater to be effective and you'll need a decent fan for airflow. At the end of it all you'll have spent far more than even a pricey heat pump dryer and it will perform worse

 

[Kmurphy]

I’m updating the insulation in the ceiling/floor of the room above, so taking the opportunity to move the washing machine and generally upgrade. But, I don’t think it’s worth insulating the whole space and putting heating out there.

A heat pump dryer might be an option, we have a condensing one but avoid it because it’s mad expensive to use.

Those electric drying boxes have fire hazard written all over them.

 

[robinbanks]

I don’t think it’s worth insulating the whole space and putting heating out there

It doesn't make sense; you said you want to dry clothes in the room by running a heater and a dehumidifier in it, but if you don't insulate it, what are you hoping your 2kW fan heater will even do, mid winter? Most the heat that would dry the clothes after you've heated the air in the room, will disappear through the walls. You'd be better off making a smaller box to heat and dehumidify, the smaller the better.. And eventually you keep conceptually shrinking the box+heater+deh down and down and down, you end up with... A condensing tumble drier (ok, it doesn't tumble, until you get the idea that to incite airflow between the clothes in your now-very-small-box, you could tumble it..)

Tumble drier fires are media hype, and likely caused by a minority of people allowing them to block solid with fluff, highly combustible. Heat pump driers might make you feel a bit more easy about the whole thing; a heat pump has a low upper limit to the temperature it can produce efficiently, around 55 C - incredibly unlikly to be a source of inition for anything you might throw in it, even petrol soaked rags

 

[Kmurphy]

my partner is dead against a tumble dryer and would rather spend the money on 50mm insulated dry wall and an electric rad…

 

[lostinthelight]

A dehumidifier doesnt work well at lower temperatures unless a decetesant model, also needs to be well closed off from external air or thats what it will be removing moisture from.
To fix battens on rough walls you could try a squirt of low expansion foam under each one and tighten full once its gone off

 

[robinbanks]

To fix battens on rough walls you could try a squirt of low expansion foam under each one and tighten full once its gone off

Yeah but remember that PIR is being proposed too - I'd just place the sheet against the dash, and fix the batten right through it; the sheet will do a good job of taking out the roughness of the dash

50mm insulated dry wall

Erk; 50mm is very low compared to what regs recommend for spaces that are at comfortable habitable temparatures, but you can work out the necessary insulation thickness from its lambda, the desired internal temperature and the getting-to-worse-case lower temperatures - that will tell you how much heat you lose through the insulation when maintaining the room at temperature X, and consequently how much heat input required from your electric rad. You'll need airflow (so budget for fans) an electric fire (vastly more inefficient than a heat pump) and a decent dehumidifier (get a continuous drain model) and at the end of it all you will notionally have built a large, but not super effective dryer that has 3 electric devices in that all pose a fire risk in their own way. I'm definitely not trying to put you off, merely to consider the reality of what you're proposing

my partner is dead against a tumble dryer

When petrol cars threatened the horse and cart, some people were dead against that too.. It all depends where people get their perspective from. There are apparently about 12 million tumble dryers in the UK and about 600 of them set on fire in 2019*, but also "According to new research, just one in twelve (8%) clean their appliance's lint filter just once a year or less - with one in 20 admitting that they never clean them at all". I wonder what the crossover between those figures really is

*ps; an approximately equal number of washing machines set on fire too, but I think you might have one of those!

 

[Kmurphy]

Erk;

Tell me about it. TBF it’s not the fire risk, it’s that the tumble drier ‘wrecks’ their clothes.

I’m working out the cost now. Battens, a basic foil and some boarding has got to be the way to go.

The ceiling will have 100mm PIR but thats more because I discovered the worst installed rock in the ceiling after some water damage and so it’s all getting an upgrade to keep the room above toasty again.

 

[robinbanks]

You'll probably find that separate insulation and plasterboard is cheaper than bonded. You can bond the two together yourself if you like, using expanding foam. Take a look for seconds grade PIR

 

[Kmurphy]

Even if I build some walls, with air gap and 75mm. I’m not building a new floor, so the concrete slab is going to be an issue - sigh

 

[robinbanks]

The floor likely wouldn't have a huge impact for your use case so you could get away with some minimal insulation on the slab and thin osb bonded on top, depending on what you plan to put on the floor

 

[Kmurphy]

I was thinking, if I have to go in that direction - Foil backed thermal roll and heavy duty rubber flooring. The ‘original ask’ was a separate utility room which was quoted as £20k+ and got rightfully dodged

 

[robinbanks]

Foil backed thermal roll and heavy duty rubber flooring

I was still thinking rigid board - roll sounds like wool or some other compressible which would be awakward on a floor because compressing it reduces its effectivenessl

 

[Kmurphy]

I was asked this morning why we can’t have underfloor heating.