The Ultimate Guide to Magnesite Floor Screed: Identification and Removal
Understanding Magnesite Floor Screed
Magnesite floor screed, a material once popular in the mid-20th century, is a type of flooring that was widely used in the UK for its insulating properties and ease of installation. Composed primarily of magnesium oxychloride, it was often mixed with wood flour, sawdust, or other organic materials to create a lightweight, durable surface. However, despite its initial popularity, magnesite floor screed has since fallen out of favour due to its susceptibility to moisture damage and the potential for causing structural issues.
What is Magnesite Floor Screed?
Magnesite floor screed is a type of flooring material that was commonly used from the 1930s to the 1960s. It is made from magnesium oxychloride cement, which is a mixture of magnesium oxide (MgO) and magnesium chloride (MgCl2). This combination creates a strong, yet flexible, material that was often used as a subfloor or screed layer beneath other types of flooring, such as tiles, linoleum, or carpet.
The addition of organic materials like wood flour or sawdust helped to lighten the mixture and improve its insulating properties. However, these organic components also made magnesite floor screed more vulnerable to moisture, which can lead to significant problems over time.
Why Was Magnesite Floor Screed Popular?
Magnesite floor screed was favoured for several reasons:
- Insulation: Its insulating properties made it an attractive option for improving the thermal efficiency of buildings.
- Ease of Installation: The material was relatively easy to mix and apply, making it a convenient choice for builders.
- Lightweight: The addition of organic materials reduced the overall weight of the screed, making it suitable for use in multi-storey buildings.
Despite these advantages, the drawbacks of magnesite floor screed have led to its decline in popularity. Understanding these drawbacks is crucial for anyone considering the purchase of a property that may contain this material.
Identifying Magnesite Floor Screed
Identifying magnesite floor screed can be challenging, especially for those unfamiliar with its appearance and characteristics. However, there are several key indicators that can help you determine whether a property contains this type of flooring.
Visual Inspection
One of the most straightforward methods of identifying magnesite floor screed is through a visual inspection. Here are some features to look for:
- Colour: Magnesite floor screed typically has a distinctive reddish-brown or pinkish hue. This colouration is due to the presence of iron oxide in the mixture.
- Texture: The surface of magnesite screed is usually smooth and may have a slightly glossy finish. However, over time, it can become pitted or cracked, especially if it has been exposed to moisture.
- Thickness: Magnesite screed is generally applied in layers that are 10-20mm thick. If you can access an exposed edge, such as at a doorway or under a removed section of flooring, you may be able to measure the thickness.
Testing for Moisture
Given that magnesite floor screed is highly susceptible to moisture damage, testing for moisture can be an effective way to identify its presence. Here’s how you can do it:
- Moisture Meter: Use a moisture meter to check the moisture content of the floor. Magnesite screed will often show elevated moisture levels, especially if it has been exposed to damp conditions.
- Visual Signs of Moisture Damage: Look for signs of moisture damage, such as discolouration, swelling, or crumbling of the screed. These issues are often more pronounced around the edges of the room or in areas where water ingress is likely, such as near windows or doors.
Professional Assessment
If you’re unsure whether a property contains magnesite floor screed, it’s always best to seek the advice of a professional surveyor. A qualified surveyor will have the expertise and equipment necessary to accurately identify magnesite screed and assess its condition.
When to Remove Magnesite Floor Screed
While magnesite floor screed can remain stable and functional for many years, there are certain situations where its removal is advisable. Understanding when to remove magnesite screed is crucial for maintaining the structural integrity and safety of your property.
Signs of Deterioration
One of the primary reasons to remove magnesite floor screed is the presence of significant deterioration. Here are some signs that indicate it’s time to consider removal:
- Cracking and Crumbling: If the screed is cracking or crumbling, it has likely lost its structural integrity and should be removed to prevent
I think I have a failed magnesite floor. I have had an asbestos test carried out and it is negative for asbestos. I have had a new wool carpet laid a year ago over a breathable underlay. However, I have noticed yellowy brown staining coming through the underlay inro the carpet. On pulling the carpet back, I can see cracks in the floor that correspond with the staining. I called in an assessor who told me that he thinks that its not a magnesite floor, but an old asphalt floor which has failed and I can just put a self-levelling compound over the floor. Can you advise me where I can find a specialist who can tell me if the floor is magnesite or asphalt. Thank you.
Given the situation described, I can provide some clarity based on my experience as a surveyor.
Magnesite floors were commonly installed in properties built between the 1930s and 1960s, particularly in flats, due to their lightweight and insulating properties. However, magnesite is known to absorb moisture over time, which can lead to issues such as cracking, staining, and degradation. The yellowy-brown staining and the cracks in your floor could be signs of magnesite deterioration. If moisture penetrates a magnesite floor, it can also cause chemical reactions, leading to corrosion of any steel reinforcement beneath.
Asphalt floors, on the other hand, are typically more durable and waterproof, but they can also crack or fail over time, particularly if subjected to structural movement or moisture ingress. The presence of cracks and staining might indicate that moisture is affecting the material beneath the floor, regardless of whether it is magnesite or asphalt.
To definitively identify whether the floor is magnesite or asphalt, I recommend seeking out a specialist who can conduct an inspection and material analysis. A visual assessment alone may not be sufficient in determining the floor type, so a more detailed analysis, potentially involving core sampling, could be necessary.
You can find a specialist by contacting:
Building Surveyors: Specifically, surveyors experienced in older properties or post-war construction are likely to be familiar with both magnesite and asphalt flooring. They will be able to assess the floor and may be able to arrange for further testing if required.
Flooring Specialists: Some flooring contractors specialise in the repair and refurbishment of older or problematic floors. They are likely to have experience in identifying and managing magnesite or asphalt issues.
Damp and Structural Specialists: Given the moisture-related staining and cracks, a damp or structural expert might be necessary to assess the extent of any moisture penetration or underlying damage.
In your case, it is critical to establish the exact cause of the floor’s deterioration. If it is magnesite, a self-levelling compound alone may not address the underlying moisture issue, and covering the problem without addressing it could lead to further damage down the line. Asphalt, if correctly repaired, may be more stable, but the cracks suggest movement or moisture that also needs to be addressed.
I recommend finding a local specialist through the Royal Institution of Chartered Surveyors (RICS) or checking platforms like Checkatrade for damp or flooring experts. A core sample or material test might be required to conclusively determine the floor type, and it’s worth seeking professional advice before carrying out repairs.
Once the floor is properly identified, the appropriate remedial action can be taken. This might include moisture control measures or full replacement of a magnesite floor if it has significantly failed.
Ensure the underlying moisture problem is resolved before any repair works to prevent recurrence of the damage.