Specification
C-C-2015 © 2015 SIMPSON STRONG-TIE COMPANY INC. PRINTED 12/14
209
DTT tension ties are safe, cost-effective connectors designed
to meet or exceed code requirements for deck construction.
These versatile DTT connectors are also load rated as a holdown
for light-duty shearwalls and braced wall panel applications.
For new construction or to make an existing current deck
code-compliant, the DTT1Z can be used as a tension-tie to satisfy
the 2015 IRC provision for a 750 lbs. lateral load connection
to the house at four locations per deck. This new code detail
permits the lateral connection from the deck joists to be made
to top plates, studs, or headers within the supporting structure,
which eliminates the need to access to the floor joists inside
the home.
The new DTT1Z fastens to the narrow or wide face of a
single 2x with Simpson Strong-Tie
®
Strong-Drive
®
SD Connector
screws or nails and accepts a
3
⁄
8
" machine bolt, anchor bolt, or
lag screw (washer required) or can be installed with the new
Strong-Drive SDWH Timber-Hex HDG screw with an integral
washer. The DTT2 fastens easily to the wide face of a single or
double 2x using Simpson Strong-Tie Strong-Drive SDS Heavy-
Duty Connector screws (included) and accepts a ½" machine bolt
or anchor bolt.
The DTT2 can be used to satisfy the IRC provision for a
1,500 lbs. lateral load connection at two locations per deck.
Additionally, the DTT2 has been tested and evaluated in deck
guardrail post applications to resist the code-specified lateral
forces at the top of railing assemblies. The DTT2 is also
available with longer 2½" Strong-Drive SDS Heavy-Duty
Connector screws (model DTT2Z-SDS2.5) to achieve higher
loads when needed.
MATERIAL: 14 gauge
FINISH: DTT1Z/DTT2Z—ZMAX
®
coating;
DTT2SS—Stainless steel; see Corrosion Information,
pages 13-15.
INSTALLATION:
• Use all specified fasteners. See General Notes.
• A standard cut washer (included) must be installed
between the nut and the seat.
• Simpson Strong-Tie Strong-Drive SDS Heavy-Duty
Connector screws install best with a low speed high
torque drill with a
3
⁄
8
" hex head driver.
• Strong-Drive SD Connector screws install with
a
1
⁄
4
" hex head driver.
• Strong-Drive SDWH Timber-Hex HDG screws install
with a
1
⁄
2
" hex head driver.
CODES: See page 12 for Code Reference Key Chart.
DTT2Z
2x8 Min.
Decking
(typ.)
4x4 post
min. (typ.)
¹⁄₂" diameter HDG
machine bolts or
threaded rods with
nuts and washers
(Simpson
RFB#4x7HDG)
Uses SDS ¹⁄₄"x1¹⁄₂"
screws (included)
Standard cut washer
required between
nut and seat
(provided)
2"
DTT2Z Installed
as a Lateral Connector
for a Deck Guardrail Post
For more information on
guardrail post connections, see
technical bulletin T-GRDRLPST
DTT1Z
6-SD#9x1½"
screws (shown) or
8-10dx1½" nails
3
⁄
8
" HDG lag screw
with HDG washer or
SDWH Timber-Hex
HDG screw (shown)
into top plate, studs,
or header
3" Min. Thread
Penetration
Typical DTT1Z Deck-to-House
Lateral Load Connection
For more information on lateral
load connections, see technical
bulletin T-DECKLATLOAD
2"
DTT2ZDeck
joist
Floor joist
(Solid 2x joist or
2x blocking)
¹⁄₂" diameter
HDG threaded
rod with nuts
and washers
Floor sheathing
nailed at 6" max.
on center to joist
with holdown
Continuous flashing
(per code), not shown
Typical DTT2Z Deck-to-House
Lateral Load Connection
For more information on lateral
load connections, see technical
bulletin T-DECKLATLOAD
1
5
⁄
8
"
1
5
⁄
8
"
3
1
⁄
4
"
6
15
⁄
16
"
DTT2Z
DTT
Deck Tension Ties
Decks & Fences
Decks & Fences
These products are available with additional corrosion protection. Additional products on
this page may also be available with this option, check with Simpson Strong-Tie for details.
1. Allowable loads have been increased 60% for wind or earthquake loading
with no further increase allowed.
2. DTT1Z installations with allowable loads below 750 lbs. do not satisfy the 2015 IRC
requirements for deck-to-house lateral load connections.
3. The Strong-Drive
®
SDWH Timber-Hex HDG screw with a minimum of 3" of thread penetration
into dry lumber has an allowable withdrawal load (160) of 1380 lbs. into SP, 1225 lbs.
into DF and 1020 lbs. into SPF/HF.
4. Load values are valid if the product is flush with the end of the framing member or
installed away from the end.
5. The guardrail post illustration above addresses an outward force on the guardrail.
An additional DTT2Z can be added at the lower bolt to address an inward force.
6. A
3
⁄
8
" HDG round washer is required when using a log screen.
Model
No.
C
L
Anchor
Dia.
Fasteners
Minimum
Wood
Member
Thickness
Allowable
Tension Loads
Code
Ref.
DF/SP SPF/HF
DTT1Z
3
⁄
4
3
⁄
8
6
or
SDWH
3
6-SD #9x1
1
⁄
2
1
1
⁄
2
840 840
1606-10dx1
1
⁄
2
910 640
4
8-10dx1
1
⁄
2
910 850
DTT2Z/DTT2SS
13
⁄
16
1
⁄
2
8-
1
⁄
4
"x1
1
⁄
2
" SDS
1
1
⁄
2
1825 1800
I6,
L8, F5
3 2145 1835
DTT2Z-SDS2.5
13
⁄
16
1
⁄
2
8-
1
⁄
4
"x2
1
⁄
2
" SDS 3 2145 2105
1
7
⁄
16
"
1
1
⁄
2
"
7
1
⁄
8
"
4
15
⁄
16
"
DTT1Z
U.S. Patent Pending
page 209