Stack a block wall up to 4 ft: base, drainage, courses, caps.
Answers
Sheet
Sheet A-1 · Garden wall
20′ wall, 3′ tall
PRO STEP
Blocks
89
large block
Courses
6
12″ buried
Base
48
bags of gravel
Drain stone
140
bags
25–38 h of work
A long weekend, plus a few business days waiting on 811.
Draft
The rules behind this Sheet are waiting for a licensed pro’s sign-off.
Permit likely needed
Most places follow the IRC (R105.2): a retaining wall needs a permit when it is over 4 ft from the bottom of the footing to the top of the wall, or when it holds up a load. This one is 4′ 9-1/2″ with the cap. Some towns are stricter. Confirm with your building department.
Call 811 first — it’s the law
Call 811 a few business days before digging (your state sets the wait). Free. Wait for the utility markings.
Drawing
Section through the wall
1
Block 8″ H × 18″ L × 12″ D. Each course sets back on the lip.
2
Cap Glued with block adhesive.
3
Drainage stone ¾″ clean stone, 12″ deep behind the wall.
4
Filter fabric Between stone and soil.
5
Base 6″ compacted gravel, 24″ wide.
6
Buried course At least 6″ below grade — keeps the toe from kicking out.
Not to scale horizontally. Setback exaggerated for clarity.
What to buy
8 items · 2 if needed
Save to your jobs to check things off in the store.
Concrete & landscape
Retaining wall block
8″ H × 18″ L × 12″ D
89 blocks
Concrete block with a rear lip that sets each course back.
Wall cap
to match the block
14 caps
Flat finishing units glued on top.
Landscape block adhesive
10 oz tube
2 tubes
Glues caps to the top course.
Base gravel (paver base)
¾″ crushed stone with fines
48 bags (0.5 cu ft)
Crushed stone with fines; compacts into a firm, level base.
Leveling sand
If needed
½″ screed under the first course
3 bags
Keep the receipt — return it if you don’t use it.
Thin screed layer to fine-tune block or pavers.
Drainage stone, ¾″ clean
¾″ clean stone, no fines
140 bags (0.5 cu ft) — or 2.6 cu yd delivered
No fines, so water drains instead of pushing on the wall.
Landscape filter fabric
3 × 50 ft roll
1 roll
Keeps soil from clogging the drainage stone.
4″ perforated drain pipe with sock
If needed
10 ft sections
3 sections
Keep the receipt — return it if you don’t use it.
Carries water out from behind the wall.
Tools
You own 0 of 16 must-haves
Tap the ones you already own. That builds your Tool Shed as you go — no setup.
Must have
The job stalls without it.
Tape measure (25 ft)
The red boxes every 16″ on the blade are stud spacing.
Mason's line + stakes
A tight string that sets a straight, level line for block courses.
Line level
A tiny level that hangs on a string line.
4-ft level
Checks plumb and level over a long span.
Torpedo level
Short level for single blocks and tight spots.
Square shovel
Cuts clean trench walls, moves gravel.
Round-point shovel
Digs.
Hand tamper
Compacts soil and gravel in small areas.
Wheelbarrow
Moves gravel, soil and block.
Landscape rake
Spreads gravel and soil level.
Rubber mallet
Seats blocks without chipping
Brick set + 3-lb hammer
Splits block for the end cuts
Work gloves
Tack strip, block and lumber shred hands.
Safety glasses
Every cut, every nail, every time.
Knee pads
Flooring and tile are all knees.
Caulk gun
Dispenses caulk and adhesive.
Rent it
Costly to buy for one job. Rent it for a day.
Plate compactor
For 20′ of base, rent one — hand tamping won’t get it tight
Rent
Concrete cut-off saw
Clean cuts on end blocks; cut wet
Rent
Nice to have
Faster or cleaner, not required.
Half-face respirator (P100)
Silica dust if you cut block
Order of work
25–38 h of work
01
Call 811 and wait for the utility markings.
02
Stake the wall line and set a string at the height of the first course.
03
Dig the trench 24″ wide × 18″ deep. Compact the bottom.
Check first
Check the trench depth at both ends against the string line.
04
Add base gravel in 2–3″ layers, compacting each one, to a flat 6″ pad.
Check first
Plate compactor on hand (rent it): compact every 2–3″ layer, or the wall settles and leans.
05
Set the first course on a thin screed of sand. Level every block side to side and front to back — take your time here.
Check first
Level every block side to side and front to back — errors on course one repeat all the way up.
06
Backfill in front of the first course. Fill 12″ behind the wall with drainage stone.
Check first
Drainage stone behind the wall, not the dirt you dug out.
07
Stack courses with joints staggered half a block. Sweep each course clean; backfill and compact behind every course.
Check first
Backfill and compact behind each course as you go.
08
Lay filter fabric between the stone and the soil; finish the top 6″ with topsoil.
09
Glue the caps down with block adhesive.
Mistakes that ruin the job
3 mistakes
1
A first course that isn’t level
Every error on course one repeats up the wall. Spend half your time on it.
2
Backfilling with the dirt you dug out
Without drainage stone, water pressure pushes the wall over within a few winters.
3
Skipping compaction
Loose base settles and the wall leans. Compact every 2–3″ layer.
Plan it
The load
To haul
15,090 lb
from the store to the room
Helpers
1
for some steps
Heaviest
Drainage stone, ¾″ clean · 140 bags · 7,000 lb
Retaining wall block · 89 blocks · 5,340 lb
Base gravel (paver base) · 48 bags · 2,400 lb
Bring a helper: unload and move materials
About 15,090 lb to move — have it delivered, or bring a helper and a hand truck or wheelbarrow.
Rent: Plate compactor, Concrete cut-off saw
When you’ll finish
Pick when you can start and how many hours you have.
Hours you can work
Each weekday evening
0
h
Each weekend day
8
h
Saved for every Sheet. Waits run overnight and on days off; work only fills the hours you have.
DIY vs hiring it out
Estimate
Typical US store prices and labor rates, not a quote. A real price can differ a lot.
Do it yourself
Materials
$1,350–$1,850
Tools to buy
16 must-haves you don’t own
Tape measure (25 ft), Mason's line + stakes, Line level, 4-ft level, …
Rentals
2
About $40–$90 a day each
Your time
25–38 h
Total
$1,350–$1,850 + tools
Hire a pro
Materials + 15%
$1,550–$2,150
Pros mark up what they buy
Labor
13.7 h × $65–$95
$890–$1,300
Their time
13.7 hours
Permits
likely needed
Total
$2,450–$3,450
Before you go
0 of 6 checked
The small stuff that causes a second trip to the store.
Gloves that grip block
Marking paint
811 ticket number (call 811 a few business days ahead)
N95 or P100 mask
Contractor trash bags
Pencil and spare knife blades
Rules used
6 rules · Draft
Every number on this Sheet comes from these rules. A licensed pro reviews each one before a Sheet is marked verified.