Bitumen on concrete and ufh

ThisIsWeird

A quick Google shows there are a number of primers available for bitumen, should you need to adhere the mat down, or add a latex levelling skim. That part seems straight forward to me.
I guess the main issue is, how high are the high spots, and how significant is this? Ie, for whichever method is used to lay the mat - glue or float - just how smooth and level does the sub floor need to be? This should be easy to find in the installation instructions.
Your decision then will likely be, how thick a latex skim is required (if at all)? The answer will usually come down to how many 'high spots' are there in the bitumen, and is it worth taking them down? If it's generally at one level, but there are raised ridges, say, between where the planks used to be, then it would probably make sense to reduce these highest ridges first. Assuming the bitumen is hard, this might be quite doable with a floor scraper, tho' it might need something motorised - not sure what. If you don't mind some hard work on yer knees, you could even 'plane' it, I suspect - you'd need to trial that it shaves off reasonably well. Perhaps wetting the floor first will help shavings not to stick?
The thought of having to remove the bitumen with either heat or chemicals is 'orrible

stuart45

V2001 said:

 Is it acting as a dpc

It does act as a DPM. it can also contain asbestos. Contact the manufacturer, as most advise against heating mats directly on bitumen.

Eldi_Dos

For peace of mind and cost I would be looking at conventional radiators, some very stylish ones available.

I have removed bitumen from a tiled vestibule,and it was hard work but had a smooth surface to work with.Cannot see how it can be done on concrete if there are any irregularities.

ThisIsWeird

stuart45 said:

V2001 said:

 Is it acting as a dpc

It does act as a DPM. it can also contain asbestos. Contact the manufacturer, as most advise against heating mats directly on bitumen.

BiB - Obviously an important step.

Do all bitumen coatings act as DPMs? Wouldn't it depend on house age? Couldn't they just be an adhesive?

stuart45

ThisIsWeird said:

stuart45 said:

V2001 said:

 Is it acting as a dpc

It does act as a DPM. it can also contain asbestos. Contact the manufacturer, as most advise against heating mats directly on bitumen.

BiB - Obviously an important step.

Do all bitumen coatings act as DPMs? Wouldn't it depend on house age? Couldn't they just be an adhesive?

Pitch was a dual purpose material for this. Primarily as an adhesive, it also helped protect the wood. Although it wasn't until the mid 60's that the DPM became part of the regs, asphalt floors were sometimes used before that as a DPM. 

V2001

So should I not take the bitumen off?

stuart45

V2001 said:

So should I not take the bitumen off?

I'd contact the Tech department at the manufacturer first and get their advice.
This problem would have come up with them quite a few times in the past.

danrv

V2001 said:

So should I not take the bitumen off?

Getting it tested would help with the decision.
If it contains asbestos, it's likely to be a small amount. £4k for pro removal I would have thought rules out that option.
I'm assuming the adhesive in my hallway is an ACM but it's not spread half as thick as shown in the pic. 
It can be done DIY with PPE, dampening down and using a scraper or heat gun. Maybe try a small area to see. 

I'd be inclined to use something like Arditex NA. Info states that it's for substrates like this and is suitable for use with UFH.

https://ardex.co.uk/product/arditex-na/

FreeBear

Is this a wet UFH heating system, or electric ?

If the latter, be prepared for a bill shock next winter - Electric UFH can be very expensive to run.

danrv

V2001 said:

There is no insulation,  I will be relying on the matts from the ufh which has a foil top which are eps 400 boards

A wet system by the look of it.