F Ball - Stopgap Green Bag (25kg) General Purpose Floor Smoothing Underlayment

Bulk Buy Discount
In stock
  • 10 items +    £16.09
  • 25 items +    £15.59
  • Available for Next Day Delivery
  • FREE Delivery when you spend over £125

F Ball - Stopgap Green Bag (25kg) General Purpose Floor Smoothing Underlayment

STOPGAP GREEN BAG is a general purpose, low odour, fast setting smoothing underlayment suitable for use in light to heavy-duty applications for preparing sound subfloors prior to the installation of new floorcoverings. It is suitable for use in clinical and biologically sensitive areas such as hospitals, laboratories, clean rooms etc. 

STOPGAP GREEN BAG is suitable for use over absorbent and non-absorbent subfloors and can be used for patch filling timber floors prior to overlaying with plywood. 

STOPGAP GREEN BAG is also suitable for application over absorbent uneven concrete and sand/cement screeds, prior to application of STOPGAP waterproof surface membranes or STOPGAP ISOLATOR. 

STOPGAP GREEN BAG is dimensionally stable and is supplied as a pre-blended dry powder and liquid which is designed for application between 3 – 20mm. 

Liquid Selection:
Use STOPGAP GREEN BAG with STOPGAP 114 Liquid over most absorbent and non-absorbent surfaces without the need to prime. Use STOPGAP GREEN BAG with STOPGAP 128 Liquid over absorbent and non-absorbent surfaces when primed with STOPGAP P131 or P121

Technical Information:

  • Appearance: Powder - 25kg lined paper sacks. Liquid - 5 litre bottles.
  • Consumption per mm thickness: 1.75kg/m2
  • Working Time @ 20°C: 15 - 25 minutes
  • Walk on hardness time @ 20°C: 90 minutes


A 25kg bag of STOPGAP GREEN BAG powder mixed with 5.0 litres of STOPGAP 114 or 128 Liquid will cover approximately 5.0m2 at a thickness of 3mm.
NoteCoverage rates are for guidance purposes only and will vary according to the condition of the subfloor.


Pour the mixed material onto the prepared subfloor and allow to flow and attain a smooth finish. Minimal work with a smoothing trowel is required. The use of a spiked roller will help eliminate entrapped air and smooth out flow lines to give a more uniform surface appearance. The mixed material can be applied at a thickness between 3mm to 20mm, but can be taken down to feathered edge if required. For best results, an overall thickness of at least 3mm should be maintained. 

STOPGAP GREEN BAG is self-smoothing, but should any imperfections remain they can be removed by rubbing with a carborundum stone when the underlayment will accept foot traffic - typically 90 minutes after application at 20°C. This time will be extended with reduced temperature i.e. approximately 3 hours at 10°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. The underlayment must be left uncovered for approximately 12 hours when used with STOPGAP 114 Liquid or 24 hours when used with STOPGAP 128 Liquid, before proceeding with the installation.

For thicknesses greater than 3mm, additional drying time will be required. When used to pre-smooth prior to the application of a STOPGAP waterproof surface membrane the underlayment should be left for a minimum of 24 hours before proceeding


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. When stored correctly, as above, and used within 6 months of the date shown on the packaging, the activity of the reducing agent added will be maintained and this product will contain, when mixed, no more than 0.0002% (2ppm) soluble chromium (VI) of the total dry weight of the cement.

Shelf Life:

Powder: 6 months in unopened bags and stored under good conditions. Liquid: 12 months in unopened bottles.

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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