<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-07-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001328581</issuerCik>
        <issuerName>BOISE CASCADE Co</issuerName>
        <issuerTradingSymbol>BCC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001317436</rptOwnerCik>
            <rptOwnerName>BOISE CASCADE HOLDINGS, L.L.C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1111 WEST JEFFERSON STREET, SUITE 300</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOISE</rptOwnerCity>
            <rptOwnerState>ID</rptOwnerState>
            <rptOwnerZipCode>83702</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2013-07-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25.8795</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19700000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2013-07-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3864062</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25.8795</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15835938</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represent shares of common stock of Boise Cascade Company (&quot;Common Stock&quot;) sold in an underwritten secondary offering.</footnote>
        <footnote id="F2">Represent shares of Common Stock repurchased by Boise Cascade Company in a stock repurchase.</footnote>
    </footnotes>

    <remarks>Boise Cascade Holdings, L.L.C. (''BC Holdings&quot;) may be deemed a director by deputization as a result of Samuel M. Mencoff, a member of the limited partner committee of Madison Dearborn Partners IV, L.P. (&quot;MDP IV&quot;), and Thomas S. Souleles and Matthew W. Norton, employees of Madison Dearborn Partners, LLC (''MDP''), serving on the board of directors of Boise Cascade Company.  Forest Products Holdings, L.L.C. (&quot;FPH&quot;) holds a majority of the voting common units of BC Holdings and has the right to appoint a majority of the members of the board of directors of BC Holdings. Madison Dearborn Capital Partners IV, L.P. (''MDCP IV'') is the controlling equityholder of FPH. MDP IV is the general partner of MDCP IV. MDP is the general partner of MDP IV. Paul J. Finnegan and Samuel M. Mencoff are the sole members of a limited partner committee of MDP IV that has the power to vote or dispose of the equity units held by MDCP IV.</remarks>

    <ownerSignature>
        <signatureName>by /s/ John T. Sahlberg, Senior Vice President, Human Resources and General Counsel</signatureName>
        <signatureDate>2013-07-31</signatureDate>
    </ownerSignature>
</ownershipDocument>
