Magnesite. is it a problem?

[shail]

Just received building inspection report. following is written with other few things:

Magnesite is present. Magnesite is present below carpet. Magnesite is a product used in the 60's and 70's below carpet in lieu of underfelt and as a noise preventative. Magnesite absorbs moisture (particularly to areas prone to moisture such as external walls, doorways and around shower recesses). Most often, spalling concrete as a result of corroding reinforcement can be anticipated. Removal is recommended. Check strata records for recent repair work carried out.

Elsewhere in the report...
Positive moisture meter reading is present to wall adjacent shower. This indicates a possible water leakage problem.

Anyone knows how bad is the magnesite?

 

[Tools]

I have never heard of it, but here is something from another forum.

Tools





OK, this is what my brain was ringing warning bells about. (The asbestos thing was a separate worry that I found when googling about magnesite flooring).

"UNIT BUILDINGS – MAGNESITE FLOORING

Unit building are often provided with a magnesite coating to the top surface of the internal floor. This type of coating was regularly used in unit construction during the 1960’s and 1970’s, but also in some buildings prior to and later to this time. The magnesite coating was installed mainly as a levelling compound to provide an adequate level surface to the floor. Additionally, this is a cork type material which is soft and provides a softer finish to the floor and was superseded by the more recent improved carpet underlays. Problems are now emerging with this magnesite that when it becomes damp, or wet, it sets up a chemical reaction with the steel reinforcing to the main part of the concrete structure, or floor. This chemical reaction sets up accelerated rust which attacks the structural core of the floor slab and building. In extreme cases, the floor in the affected areas can noticeably lift. The problems occurs when water entry transpires, particularly around leaking windows or patio door units. Additionally, a chemical reaction can be set off particularly if the internal carpets are steam cleaned on a regular basis. The extent of any future repairs, or replacement, would depend upon further exploratory works to the majority of the building and can involve major rectification costs. Some strata managers are recommending that the magnesite be removed when the unit is refurbished."

From here:
http://www.buildreport.com.au/news/2003_03.htm#magnesite

As this relates to a unit I'm intending to buy I've resolved to get a full building inspection (rather than rely on the strata report).

Thanks for all the contributions! It's good to get feedback from those with more scientific knowledge than myself. Cheers!

 

[shail]

Thats the thing. I never herd either. I spoke to my solicitor and he said he knows that 99 % people dont know about this.

 

[asdf]

We had it in our floors when renovating. The water affected parts simply crumbled away like Weetbix. Got strata to scrape up and fix it as luckily the rot was due to water seeping in the front balcony and also prior leak from neighbour before we bought the unit. Could've easily gone the other way cos floors are deemed ours. Then we wanted to floorboard and was told it would cost a fair bit to remove all magnesite by digging it all up. Strata wouldn't pay for this. Flooring guys advised if theres no more leaks, then it would be fine simply laying boards over the top. We decided this was easiest. Strata ended up paying for half our floors cos the magnesite damaged the front and would've have to fix the ugly parquette in the living room anyway. Great result at the end but a real pain.

 

[DaveM]

Holy thread necro batman! Spam reported!

 

[Kristine..]

Hello Shail

Shail, when I took up the carpets at Myrtle Cottage the whole of the living area was covered in terra-cotta coloured Magnesite and in one of the bedrooms, in black coloured Magnesite

The neighbours told me that all owners of the house had complained about the cold, so I guess someone had invested in this layer of insulation across the two most vulnerable rooms. I scraped it off with the back of a shovel, sweeping it up as I went. (read: Clouds of very fine dust, Cough! Cough!)

Underneath, the floor boards were in mostly good condition, except where borer had got into the boards in a couple of spots. Borer is very common in timber floors so not a real problem in this house.

The tiled shower recess and general floor in the bathroom, which was at the most shallow above ground end of the house and with no sub floor ventilation, was rotted to powder and held together by the cement sheet and tiles laid on top of it, but that floor had no Magnesite and the whole of the house had not had any maintenance for many years (plastic plumbing eaten away by rats, liquid gold pouring out of the taps and other delights!)

While I was renovating nobody knew anything about this product or treatment, so I had to guess what it was all about

Good on you for finding out the product name and a bit of the history of it's uses. I noticed, when I was scraping and shovelling, that when I breathed it in that it tasted like clay. Muslin was taped over the top and then the carpet was on top of that.

Not very flexible, but heat, cold, draft and sound insulating. it would have been quite an investment by the householder and it seemed to be a shame to remove it but the house needed to be stripped right out so it all had to go

Cheers
Kristine