F Ball - Stopgap 1200 Pro (20kg + 5ltr) High Performance Smoothing Underlayment

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In stock
  • 10 items +    £41.56
  • 25 items +    £40.27
  • Available for Next Day Delivery
  • FREE Delivery when you spend over £125

F Ball - Stopgap 1200 Pro (20kg + 5ltr) High Performance Smoothing Underlayment

STOPGAP 1200 is a low odour, fast setting, fast drying, two component smoothing underlayment suitable for preparing sound internal subfloors prior to the installation of new floorcoverings. 

STOPGAP 1200 is particularly suitable for use over old adhesive residues (including bitumen and carpet tile tackifiers) without the need for priming. STOPGAP 1200 can be used for patch filling timber floors prior to overlaying with plywood. It is suitable for use in clinical and biologically sensitive areas such as hospitals, laboratories, clean rooms etc.

STOPGAP 1200 is unaffected by moisture and is suitable for application over damp, clean, uneven concrete and sand/cement screeds, prior to application of STOPGAP waterproof surface membranes or STOPGAP ISOLATOR MEMBRANE. 

STOPGAP 1200 is also suitable for use over a wide range of other subfloor types including STOPGAP waterproof surface membranes, sand/cement screed, concrete, granolithic, terrazzo, asphalt, steel, old vinyl asbestos tiles, epoxy and polyurethane resins, ceramic and quarry tiles.

Technical Information:

  • Appearance: 20kg lined paper sacks. 5 litre bottles.
  • Working Time @ 20°C: 15-20 minutes
  • Walk on hardness time @ 20°C: 60 minutes
  • Consumption per mm thickness: 1.98 kg/m2
  • Application thickness: from 2 - 20mm



A 20kg bag of STOPGAP 1200 Powder mixed with 5.0 litres of STOPGAP 1200 Liquid will cover approximately 5.0m² at a thickness of 2 - 3mm. Note: Coverage rates are based on 5.0 litre addition and will vary according to the condition of the subfloor.


Mix only with STOPGAP 1200 Liquid. 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 2mm to 10mm unfilled or up to 30mm filled, 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 1200 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 60 minutes after application at 20°C. This time will be extended with reduced temperature i.e. approximately 2 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. On all surfaces, at a nominal 2 - 5mm thickness, the compound will be ready to receive most floorcoverings from 4 hours. At an applied thickness of 6 - 10mm, most floorcoverings can be installed after 24 hours. For thicknesses greater than 10mm and up to 30mm, the drying time will be extended up to 7 - 14 days. 

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.


If applying to asphalt, ensure a minimum application of 3mm and a maximum application of 6mm is used and is applied uniformly. Not suitable for use over adhesive residues beneath surface damp proof membranes or over water softenable adhesive residues - these residues must be fully removed.


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:

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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