F Ball - Stopgap 1100 Gypsum (22kg) Calcium Sulphate Based Underlayment

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  • 10 items +    £40.24
  • 25 items +    £39.00
  • Available for Next Day Delivery
  • FREE Delivery when you spend over £125

F Ball - Stopgap 1100 Gypsum (22kg) Calcium Sulphate Based Underlayment

STOPGAP 1100 GYPSUM is a self-levelling smoothing underlayment designed specifically for application over sound calcium sulphate (e.g. anhydrite) screeds prior to the installation of new floorcoverings. 

STOPGAP 1100 GYPSUM is dimensionally stable and is supplied as a pre-blended dry powder, which is designed for application between 2 – 10mm. It is protein-free which allows it to be used in biologically sensitive areas such as hospitals. 

STOPGAP 1100 GYPSUM is calcium sulphate based and is particularly compatible for smoothing and levelling similarly contructed screeds but may also be used over a wide range of other subfloor types including STOPGAP waterproof surface membranes, sand/ cement screeds, concrete, sound asphalt, granolithic, terrazzo, epoxy and polyurethane resins, ceramic and quarry tiles. 

STOPGAP 1100 GYPSUM can be pump applied up to 1500m2 per day, dependent upon manpower, thickness applied and equipment used.

Technical Information:

  • Appearance: Lined paper sack
  • Consumption per mm thickness: 1.60 kg / m2
  • Working Time @ 20°C: 20 - 30 minutes
  • Setting Time @ 20°C: 2 hours
  • Coverage (approx.): A 22kg bag of STOPGAP 1100 GYPSUM mixed with 5.5 litres of clean water will cover approximately 5.0m² at a thickness of 2-3mm.  
    Note: Coverage rates will depend on the condition and absorbency of the subfloor


Pour the mixed material onto the prepared substrate and allow to flow and attain a smooth finish. Minimal work with a smoothing trowel is required. A spiked roller should be used to eliminate entrapped air and smooth out flow lines to give a more uniform surface appearance.

The mixed material should be applied at a thickness between 2 to 10mm, but can be taken down to a feather edge if required. For optimum smoothing and levelling characteristics, an overall thickness of at least 3mm should be maintained. 

STOPGAP 1100 GYPSUM is self-smoothing, but should any imperfections remain they can be removed by rubbing with a carborundum stone when the compound will accept foot traffic – typically 2 hours after application at 20°C.

For any areas under question please consult the F Ball Technical team.


Drying is dependent on the absorbency of the subfloor, ambient temperature and humidity. On all surfaces, at a nominal 3mm thickness, the compound will be ready to receive textile floorcoverings after 24 hours and resilient floorcoverings after 48 hours. For greater thicknesses allow a further 1 day drying time per mm. 

At thicknesses greater than 20mm (filled) ensure that the moisture content is less than 75% RH, or 0.5% determined using the Calcium Carbide (CM) method, before applying any type of floorcovering.


Suitable steel smoothing trowel, spiked roller, mixing bucket, electric drill and power whisk. Wash tools with water immediately after use.


This product must be stored under cover, in unopened bags clear of the ground in cool dry conditions, protected from frost and excessive draught. Dampness will reduce the shelf life and may cause the powder to set in the sack

Shelf Life:

6 months in unopened bags and stored under good conditions.

Delivery Information

We aim to dispatch all orders within 2 working day of receipt. Occasionally public holidays, weekends, weather events, or extremely busy periods may result in extended delivery times. In these circumstances, we will endeavour to communicate with you about the delay and resolve and resulting issues.

Please note that we do not make delivery date promises, however:

- Orders placed before 1pm on a weekday will be processed the same day.

- Orders placed after 1pm on a weekday will be processed the following morning. 

- Orders placed after 1pm on Thursday will be processed and dispatched the following day and out for delivery the following Monday (if Next Day Delivery is selected).

- Orders placed after 1pm on Fridays will be processed and dispatched on the following Monday.

For more information about our Shipping & Delivery services click HERE


UK Mainland Delivery Options:


Free Delivery: Applicable for orders of £125 excl. VAT and above
(Monday – Friday, excluding public holidays)


Collect From Store: 41 Markfield Road, London N15 4QA
(Monday – Friday, 9am–5pm excluding public holidays)


Standard Delivery: 3-5 Working Days
(Monday – Friday, excluding public holidays)


Express Delivery: Next Working Day
(Monday – Friday, excluding public holidays)

Out Of Zone Delivery Surcharges:

Isle of Wight

£12.50 per item (3-5 Working Days)

Isles of Scilly

£12.50 per item (3-5 Working Days)

Northern Ireland

£25.00 per item (3-5 Working Days)

Western Isles

£25.00 per item (3-5 Working Days)

Shetland Isles

£30.00 per item (3-5 Working Days)


£30.00 per item (3-5 Working Days)

Isle Of Man

£30.00 per item (3-5 Working Days)

Channel Islands

£30.00 per item

Republic of Ireland

Not Available


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