Deck Mud Calculator

Deck mud calculator for flat mortar beds and sloped shower pans, giving bags of Quikrete or Sika mix or of sand and portland for a site mix, plus mixing water, metal lath and cost.

Bags of Mix for a Deck Mud Calculator Estimate

A 50 lb bag of Quikrete Deck Mud makes 0.41 cu ft of packed mortar, so a 6 × 5 ft floor bed 1 in thick takes 2.5 cu ft, or 2.75 cu ft with 10% waste, and that rounds up to 7 bags.

$$Bags=\lceil \frac{A\times (d/12)\times (1+w)}{Y}\rceil$$

A is the bed area in square feet, d is the average bed depth in inches, w is the waste allowance as a decimal and Y is the yield of one bag in cubic feet. Bag yield, not bag weight, sets every deck mud calculator count.

Every bag yield in this deck mud calculator math comes from the maker's own data sheet: Quikrete Deck Mud (May 2022), Quikrete Floor Mud (April 2024) and SikaTile 910 FloorMud (September 2026).

The same 2.75 cu ft of mortar costs 350 to 400 lb of bags depending on brand, because bag rounding never lands evenly. On a second-floor bath that weight goes up the stairs by hand, so the bag size that rounds closest to your volume saves both money and trips.

From those deck mud calculator yields, packed mortar weighs about 120 to 128 lb per cubic foot, or roughly 10 lb per square foot at 1 in thick. That is the dead load a mortar bed adds to the floor framing under it.

Coverage Chart for Deck Mud Bags by Depth

A 50 lb bag of deck mud covers about 9.8 sq ft at 1/2 in, 4.9 sq ft at 1 in and 2.5 sq ft at 2 in. Coverage halves every time the depth doubles, so depth moves a deck mud calculator total more than area does.

Coverage figures are before waste. For deck mud calculator square feet totals, divide the bed area by the chart value and add 10% for tamping, low spots and the mud left in the bucket.

As a check on the deck mud coverage chart, Sika prints 6.25 sq ft at 3/4 in for its 50 lb bag, which matches the row above. Quikrete prints yield in cubic feet only, so the Quikrete columns are that yield spread over each depth.

Shower Pan Mud With a Sloped Bed

For a shower pan, a deck mud calculator estimate has to account for slope: a pan with a center drain holds more mud than the average of its thin and thick edges suggests. With the drain at 1 in and the walls at 1-3/4 in, the true average depth is 1-1/2 in, not 1-3/8 in.

$$d_{avg}=d_{drain}+\frac{2}{3}\times (d_{wall}-d_{drain})$$

d_drain is the bed thickness at the drain and d_wall is the thickness at the level perimeter. The slope forms an upside-down pyramid of empty space above the drain, which takes one third of the rise, leaving two thirds as mortar wherever the drain sits.

In deck mud calculator terms, a linear drain along one wall slopes one way, so its bed is a wedge and the plain average is right: (d_drain + d_wall) ÷ 2. A 60 × 36 in pan with the drain on a 60 in wall takes 5 bags of 50 lb deck mud at 1 in to 1-3/4 in.

The perimeter height in a shower pan mortar calculator estimate comes from the slope. The plumbing codes require shower floors to slope at least 1/4 in per foot toward the drain, so measure from the drain to the farthest corner and multiply by 1/4 in to get the rise.

Every row in this deck mud calculator table starts at 1 in thick at the drain and adds 10% waste. The 48 × 48 in pan is where the plain average of thin and thick edges buys one bag short, leaving a corner short of mud before the last pass.

A traditional liner shower uses two layers: a sloped pre-slope under the liner and an even final bed over it, which follows the same slope. On the 48 × 48 in pan, a 1-1/4 in final bed over the pre-slope brings the deck mud calculator total to 3.99 cu ft, or 10 bags of 50 lb deck mud.

The lath counts for one layer only, so add mesh for the final bed if your system calls for it. To set the wall line from the drain distance and check the slope against code, the Shower Pan Slope Calculator works out the drop for center, off-center and linear drains.

Sand and Portland Cement Site Mix

For a deck mud ratio calculator check, a site-mixed bed takes about one 94 lb bag of portland cement for every 60 sq ft at 1 in thick in a 1:5 mix. Damp sand fills roughly the finished mortar volume, and the cement fills the gaps between the grains.

$$Cement=\frac{V}{k}Sand\approx V$$

V is the packed mortar volume in cubic feet, k is the parts of sand per part of cement, and one 94 lb bag of portland is 1 cu ft. A 5-gallon bucket holds 0.67 cu ft, the usual way to count sand on site.

The cost gap in a deck mud calculator comparison is wide. At $15 per bag of deck mud, $17 per bag of portland and $55 per cubic yard of sand, the 100 sq ft bed costs $420 in bags or about $74 site-mixed. Bagged mix wins on small showers, where one cement bag and a few buckets of sand are a lot of fuss for 3 cu ft.

A 1:5 mix is the leaner floor mortar, and a 1:4 mix is the richer blend many setters use for shower receptors. The 4 to 1 mud bed mix needs 25% more cement for the same bed, as the 1,000 sq ft row shows.

Thickness Limits, Lath and Cure Time

Most bagged mud beds run from 1/2 in to 2 in thick, the range any deck mud calculator depth should stay inside. Sika lists 1/2 to 2 in for SikaTile 910, and Quikrete gives bonding methods for Deck Mud from 1/2 to 1 in with its acrylic fortifier and from 1 to 2 in with its bonding adhesive.

Beds thinner than 1/2 in crack and lose bond, so a floor that needs less fill wants a thin-set or leveling product instead. Deeper than 2 in, place the fill in layers or check the bag for a higher limit before a single pour.

Bonding a thin bed to a slab changes the deck mud calculator shopping list. Quikrete has you replace half the starting water in Deck Mud with its Acrylic Fortifier for beds 1/2 to 1 in, about 2-5/8 pt per 50 lb bag,.

For 1 to 2 in, Quikrete coats the slab with its Concrete Bonding Adhesive instead, never both. Floor Mud takes 3 pt of fortifier per 60 lb bag or 4 pt per 80 lb bag.

Over wood, the bed needs metal lath. Quikrete's Deck Mud sheet says ANSI requires lath over wood, and Sika calls for at least 2.5 lb metal lath over roofing felt or building paper, fastened every 8 in.

Lath belongs in the same deck mud calculator order: a 27 × 96 in sheet of diamond lath covers 18 sq ft, so a 30 sq ft floor takes 2 sheets with 10% for laps. A 36 × 48 in shower pan takes 1 sheet.

Cure times differ by product. Quikrete cures Deck Mud and Floor Mud for 5 days at 70°F or 7 days at 50 to 70°F and protects them from freezing for 48 hours, while Sika states SikaTile 910 cures in 24 hours.

Water, Weight and Mixing Deck Mud

A 50 lb bag of Quikrete Deck Mud starts at 5-1/4 pints of water and must not pass 7-1/4 pints. The mix should hold its shape when squeezed, the damp-snowball test, without water running out.

Water is the one quantity no deck mud calculator figure fixes in advance, since sand moisture varies, so start with the low figure and add water a cup at a time. Mud that is too wet slumps on the slope and shrinks as it dries, which opens low spots that tile then has to bridge.

Floor mud and deck mud are the same kind of product, a dry-pack sand and portland mortar for beds under tile. The names differ by brand, and the Quikrete versions differ mainly in bag size and yield.

Self-leveling underlayment is a different material. It flows to flat and cannot hold a slope, so it suits a flat floor fill but never a shower pan, and it prices by its own coverage chart.

Large Floors: 1,000 Sq Ft of Mud Bed or Concrete

At large scale, deck mud calculator math still works by volume: a 1,000 sq ft mortar bed 1 in thick takes 83.3 cu ft of mud, or 91.7 cu ft with waste. That is 224 bags of 50 lb deck mud, 139 bags of 80 lb floor mud, or 19 bags of portland and 3.4 cu yd of sand in a 1:5 site mix.

A concrete slab is a different job measured in cubic yards, outside any deck mud calculator estimate. For 1,000 sq ft, ready-mix concrete comes to 9.26 cu yd at 3 in, 12.35 cu yd at 4 in, 15.43 cu yd at 5 in and 18.52 cu yd at 6 in, before any allowance for over-excavation.

A mud bed is a setting bed for tile, never a structural slab, so it does not replace concrete where a slab is needed. For the joint compound on the walls of the same room, the Drywall Calculator counts mud and tape.

The tile that goes on the finished bed has its own order. The Tile Calculator counts tiles and boxes, and the Adhesive Coverage Calculator sizes the thinset to bond them to the cured bed.